JIOIT  Oi?1   STUM         >D  MD 
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PINE 
.0.  Donk,  C.i.  Snattuok 

.1).  tarsia  11 
.  ,  .  U  3ul.  1005  Dec.  1921 


- Forestry.  Main  Lihrai 


•s>, ,  ysim 

H 


UNITED  STATES  DEPARTMENT  OP  AGRICULTURE 
BULLETIN  No.  1003 


Contribution  from  the  Bureau  of  Chemistry 
W.  G.  CAMPBELL,  Acting  Chief 

And  the  University  of  Idaho,  A.  H.  UPHAM, 


Washington,  D.  C. 


December  5, 1921 


THE  DISTILLATION  OF  STUMPWOOD 

AND  LOGGING  WASTE  OF  WESTERN 

YELLOW  PINE 

By 

M.  G.  DONK,  Assistant  Chemist 
Leather  and  Paper  Laboratory,  Bureau  of  Chemistry 

C.  H.  SHATTUCK,  Professor  of  Forestry,  and  W.  D.  MARSHALL 
Research  Fellow,  Forestry  Department,  University  of  Idaho 


CONTENTS 


Pag? 

Importance  of  western  yellow  pine    .  .  1 

Distribution  of  western  yellow  pine  .   .  2 

Purpose  of  investigation 13 

Taking  samples 15 

Distillation  of  samples 22 

Crude  products  of  retort  distillation  .   .  31 
Products    obtained  ih   refining   crude 

turpentine 37 

Calculation  of  yields  of  refined  turpen- 
tine and  pine  oil ., 41 

Commercial  distillation  processes  ...  43 


Page 
Feasibility  of  distilling  western  yellow 

Pine 46 

Relation  of  wood  distillation  to  land 

clearing 51 

Small,  semi-portable  wood-distilling 

plants 53 

Use  of  oil  for  ore  flotation 54 

Refining  crude  wood  turpentine  ....  56 

Summary 67 

Literature  cited 69 


WASHINGTON 

GOVERNMENT  PRINTING  OFFICE 
1921 


UNITED  STATES  DEPARTMENT  OF  AGRICULTUR 

BULLETIN  No.  1003 


Contribution  from  the  Bureau  of  Chemistry 
W.  G.  CAMPBELL,  Acting  Chief 

And  the  University  of  Idaho,  A.  H.  UPHAM 
President 


Washington,  D.  C. 


December  5,  1921 


THE  DISTILLATION  OF  STUMPWOOD  AND  LOGGING 
WASTE  OF  WESTERN  YELLOW  PINE. 

By  M.  G.  DONK,  Assistant  Chemist,  Leather  and  Paper  Laboratory,  Bureau  of 
Chemistry,  C.  H.  SHATTUCK,  Professor  of  Forestry,  and  W.  D.  MARSHALL, 
Research  Fellow,  Forestry  Department,  University  of  Idaho.1 


CONTENTS. 


Importance  of  western  yellow  pine 

Distribution  of  western  yellow  pine- 
Purpose   of   investigation 

Taking    samples 

Distillation  of  samples 

Crude  products  of  retort  distillation- 
Products  obtained  in  refining  crude 

turpentine 

Calculation  of  yields  of  refined  tur- 
pentine and  pine  oil 


Page. 

2 
13 
15 
22 
31 

37 

41 


Page. 

Commercial  distillation  processes 43 

Feasibility  of  distilling  western  yel- 
low pine 46 

Relation  of  wood  distillation  to  land 

clearing- 51 

Small,    semi-portable    wood-distilling 

plantjs 53 

Use  of  oil  for  ore  flotation 54 

Refining  crude  wood   turpentine 56 

Summary 67 

Literature   cited—  69 


IMPORTANCE  OF  WESTERN  YELLOW  PINE. 

Western  yellow  pine  (Pinus  ponderosa)  is  the  most  widely  dis- 
tributed of  the  western  commercial  softwoods  (4,  10) 2  (fig.  1). 
The  Forest  Service  estimates  the  amount  of  standing  timber  of  this 
species  to  be  approximately  335,000,000,000  board  feet,  or  more  than 
that  of  any  other  species  except  Douglas  fir  (6).  The  reported  cut 
for  this  species  for  1917  was  1,862,914,815  board  feet.  This  repre- 
sents an  area  of  more  than  350,000  acres  of  land  annually  cleared 
and  left  covered  with  stumps  after  logging  operations.  About  one- 
third  of  this  is  within  the  national  forests  and  is  generally  of  little 
value  for  agriculture,  because  of  the  roughness  of  the  land.  Much 
of  the  remaining  two-thirds,  however,  is  valuable  for  crops. 

1  The  sections  on  the  importance  and  distribution  of  the  western  yellow  pine  are  by 
C.  H.  Shattuck.     The  report  of  the  investigation  is  by  M.  G.  Donk. 

2  The   numbers   in    parenthesis   throughout   this  bulletin   refer   to   the  bibliography  on 
page  69. 

60953°— 21 1 


^96093 


2  BULLirirc:  ;rv.:  m$rA.Kt"rtr.NT  or  Acuirri/rrnr.. 


Removing  the  stumps  is  arduous  Mini  costly  (8),  and  so  far  they 
have  l»een  considered  to  be  worthless  after  removal.  Any  process 
which  may  serve  to  reduce  the  cost  of  clearing  the  laud  or  lead  to 
the  discovery  of  a  profitable  use  for  the  stumps  is,  therefore,  worthy 
of  careful  consideration.  Observations  on  the  methods  of  utilizing 
the  more  resinous  portions  of  the  yellow7  pine  of  the  South  in  the 
manufacture  of  wood-distillation  products  su^c-ted  the  possibility 
that  the  western  species  might  serve  the  same  purpose,  as  these  trees, 
especially  the  stumps,  are  often  quite  resinous. 

It  is  well  known  that  western  yellow  pine  was  used  in  California  as 
a  profitable  source  of  turpentine  during  the  Civil  War  (13).  In 
speaking  of  turpentine  obtained  from  western  yellow  pine.  Schorger 
(7)  says:  "There  is  no  reason  to  suppose  that  both  the  California 
and  the  Ari/ona  oils  will  not  serve  the  purposes  for  which  ordinary 
turpentine  is  commonly  used."  According  to  Betts  (2),  nearly  as 
much  turpentine  and  rosin  was  obtained  from  western  yellow  pine 
as  from  the  pines  of  the  Southeast.  Wenzell  (5)  states  that  the  odor, 
specific  gravity,  and  boiling  point  of  oleoresin  from  Pinus  ponderosa 
correspond  with  those  of  the  common  oil  of  turpentine.  It  is  there- 
fore reasonable  to  suppose  that  turpentine  operations  in  the  large 
tracts  of  virgin  pine  timber  in  the  West  will  be  undertaken  within  a 
few  years,  because  of  the  rapid  cutting  of  the  yellow  pine  of  the 
South. 

DISTRIBUTION  OF  WESTERN  YELLOW  PINE. 

For  convenience  the  chief  areas  of  western  yellow  pine  may  be 
grouped  as  follows  : 

(1)  Arizona  and  New  Mexico. 

(2)  California. 

(3)  Oregon  jind  Washington. 

(4)  Idaho,  Montana,  and  Utah. 

(5)  Colorado,  South  Dakota,  and   Wyoming. 

For  want  of  accurate  data,  no  estimates  covering  the  quantities  of 
this  species  annually  cut  for  fuel  and  uses  other  than  for  lumber  are 
given,  although  this  amount  is  known  to  be  considerable.  Neither 
is  any  account  taken  of  the  distillation  material  to  be  derived  from 
"fat"  limbs  and  "pitchy"  butts. 

The  estimates  of  stands,  and  therefore  of  stumps,  in  many  of  the 
States  are  low  because  the  results  of  the  cruises  of  much  privately 
owned  timber  were  not  obtainable. 

The  problem  of  the  better  utilization  of  this  species  is  by  no  means 
confined  to  Idaho.  Tables  2  to  1-J  and  the  map  (fig.  1)  furnish  con- 
clusive proof  of  the  enormous  quantities  of  yellow-pine  stumps  to  be 
had  in  several  Western  States.  It  will  not  be  profitable  to  work  up 
by  distillation  methods  any  but  the  more  resinous  of  the  stumps, 
"  fat  "  limbs,  and  "  pitchy  "  butts.  A  complete  field  survey  of  each 


DISTILLATION 


3 


region  to  determine  the  stand  or  number  of  rich  resinous  stumps  and 
the  practicability  of  profitable  distillation  must  be  left  to  those  in 


FIG.  1. — Geographic  distribution  of  Pinus  ponderosa. 

the  various  regions  who  plan  to  enter  the  field  of  wood-distillation 
from  a  commercial  standpoint.  Such  a  survey,  however,  should  al- 
ways be  made  before  undertaking  distillation  in  any  section. 


•  ;/  •  •    • 

P,    PK£ARTJVfENT  OF   AGRICULTURE. 


ARIZONA  AND  NEW  MEXICO. 

Total  area  in  the  national  forests acres__          *  4, 571, 425 

Total  stand  in  the  national  forests board  feet—  17,002,000,000 

Total  annual  cut  (1917) , do 154,  2J)7, 815 

Total     area     annually     cleared     (if    clear     cutting    is     em- 
ployed)   acres—  38,  574 

Total  annual  volume  of  stumpwood cords *  77, 148 

For  average  stands  the  number  of  trees  over  18  inches  varies  from 
85  to  12,  and  the  number  of  those  over  24  inches  varies  from  7  to  9 ; 
heavy  stands  have  from  12  to  30  trees  18  inches  and  over,  and  from 
11.5  to  20  trees  24  inches  and  over. 

Since  500  board  feet  is  a  liberal  average  volume  for  a  yellow-pine 
tree  22  inches  in  diameter  at  breast  height,  or  24  inches  on  the  stump 
(3,  13),  stands  of  5,000  feet  an  acre  would  contain  10  trees  averaging 
24  inches  on  the  stump.  The  average  stand  over  Arizona  and  Xew 
Mexico  being  approximately  4,000  board  feet  for  all  the  area  covered 
with  yellow  pine,  the  average  number  of  24-inch  stumps  an  acre  would 
be  8.  Many  thousands  of  acres  show  stands  above  5,000  feet,  the 
actual  number  of  trees  24  inches  and  over  being  from  10  to  15  to  the 
acre. 

It  is  evident,  therefore,  that  this  region  has  future  possibilities 
from  the  standpoint  of  wood  by-products,  if  it  is  found  that  a  fair 
percentage  of  the  stumps  are  rich  in  resin.  No  account  has  been 
taken  of  the  material  obtainable  from  "fat"  limbs  or  "pitchy"  butts, 
and  only  the  timber  on  national  forests,  where  accurate  cruises 
have  been  made,  is  here  considered.  Though  no  figures  are  avail- 
able for  the  timber  on  private  holdings,  Indian  lands,  and  the  pub- 
lic domain,  it  is  known  that  these  areas  are  quite  extensive,  and  many 
of  the  stands  are  average  or  better. 

CALIFORNIA. 

Total  area acres—  10,000,000 

Total  stand board  feet__  85,000,000,000 

Total  annual  cut   (1917) do 154,297,815 

Total  area  annually  cleared  ( if  rlcar  cutting 

is  employed) acres 38,574 

Total  annual  volume  of  stumi»\vood cords 4  77, 148 

California  has  about  10,500,000  acres  of  commercial  yellow  pine, 
with  from  85,000,000,000  to  90,000,000,000  board  feet,  or  from  8,000 
to  12,000  board  feet  an  acre.  Trees  above  12  inches  in  diameter,  breast 
high,  have  an  average  diameter  of  38  inches,  or  approximately  41 
inches  on  the  stump,  for  which  reason  the  yellow-pine  trees  of  Cali- 
fornia are  the  largest  known.  Since  the  species  usually  grows  in 
mixed  stands,  the  number  of  trees  an  acre  is  low.  The  pitch  content, 
however,  is  higher  than  that  in  any  other  section.  As  the  yellow 
pine  in  California  is  the  heaviest  known  (Table  1),  the  amount  of 
"pitchy"  wood  can  safely  be  takvn  as  average  or  better. 

National    forests   only.  '  1  '<>r  roducing  factors  s**'  Table  d. 


DISTILLATION   OF   STUMPWOOD. 


TABLE  1. — Stands  of  western  yellow  pine  in  California,  Oregon,  and  Washing- 
ton, ivith  reduction  factors  for  various  volumes  and  diameters  of  trees  and 
stumps* 


Diameter. 

Average  volume— 

Reduc- 

Reduc- 
tion 

Breast 
high. 

tion, 
breast 
height  to 

Stump 
high.* 

Of 
trees. 

Of 
stumps. 

units  for 
different 
volumes 

stump 
height. 

and  di- 
ameters. 

Inches. 

Inches. 

Inches. 

Bd.ft. 

Cords. 

22 

2 

24 

500 

0.25 

1 

23 

2 

25 

600 

24 

2 

26 

750 

.375 

1.5 

25 

2 

27 

850 

26 

2 

28 

950 

26.5 

2 

28.5 

1,000 

.5 

2 

27 

2 

29 

1,150 

28 

2.5 

30.5 

,250 

.625 

2.5 

29 

2  5 

31  5 

350 

30 

2  5 

32.5 

,425 

30.5 

2.5 

33 

,500 

.75 

3 

32 

2  5 

34.5 

,600 

32  5 

2  5 

35 

,750 

3.5 

33 

2.5 

35.5 

,850 

.875 

33  5 

2  5 

36 

,925 

34 

3 

37 

2,000 

1 

4 

35 

3 

38 

2,150 

36 

3" 

39 

2,250 

1.125 

4.5 

37 

3 

40 

2,400 

38 

3 

41 

2,500 

1.25 

5 

39 

3.5 

42.5 

2,600 

40 

3.5 

43.5 

2,750 

.375 

5.5 

41 

3.5 

44.5 

3,000 

.5 

6 

41.5 

3.5 

45 

3,250 

.625 

6.5 

42 

3.5 

45.5 

3,500 

.75 

7 

43 

3.5 

46.5 

3,750 

.875 

7.5 

44 

3  5 

47  5 

3  900 

45 

4 

49 

4,000 

2 

8 

1  This  working  table  must  be  adapted  by  the  user  to  meet  the  variations  from  the  normal  stand  as  they 
are  found  to  occur.  The  volumes  inboard  feet  represent  close  approximations  of  the  averages  of  all 
obtainable  volume  tables  for  the  regions  named.  The  volumes  in  cords  are  taken  from  measurements  of 
corded  stumpwood  in  various  regions,  and  are  as  conservative,  when  the  wood  is  split  for  the  retort,  as 
those  used  for  volume,  B.  M. 

«  The  height  of  the  stump  is  here  assumed  to  be  18  inches.    For  higher  stumps  the  diameter  would  be 

duced  according  to  the  scale,  as  given  in  columns  5  and  6. 


TABLE  2. — Sample  cruises  of  California,  yellow  pine  from  different  parts  of  the 
State,  with  volume  and  acre  equivalent  in  number  of  stumps  of  various  diam- 
eters required  to  produce  the  given  yields  (area  covered,  6,400  acres,  average 
xtand,  or  slightly  better).1 


Location. 

Volume 
per  acre. 

Number  stumps. 

Per  cent 
total 
stand. 

24- 
inch. 

28.5- 
inch. 

37- 
inch. 

Eldorado  T  8  N   R  15  E,  sec.  35 

Bd.ft. 
10,  082 
10,  501 
18,236 
12,  253 
12,  444 
9,503 
5,870 
10,  518 
17,163 
12,  276 

20.00 
21.00 
36.40 
2450 
24.88 
19.00 
11.74 
21.02 
34.32 
24.55 

10.00 
10.50 
18.20 
12.25 
12.44 
9.50 
5  87 
10.51 
17.16 
12.27 

5.00 
5.25 
9.10 
6.12 
6.22 
4.80 
3.92 
5.25 
8.58 
6.11 

83.6 
64.7 
46.4 
68.5 
87.6 
26.9 
71.6 
83.4 
72.1 
47.4 

Lassen,  T  25  N,  R  14  E,  sec.  24  

Lassen,  T27N,  R  10  E  sec.  5 

Las«en  T  32  N   R  8  E  sec  — 

Modoc,  T  46  N,  R  15  E,  sec.  32..  . 

Plumas  T  23  N   R  9  E,  sec.  5 

Sequoia,  T  13  S,  R  19  E,  sec.  19 

Sierra,  T  5  S,  R  21  E,  sec  18. 

Sierra,  T  6  S,  R  24  E,  sec.  27  

Stanislaus,  T  4  N  R  18  E,  sec.  17  . 

Average  for  6,400  acres  

11,884 

23.75 

11.88 

5.94 

64.5 

1  Estimates  furnished  by  T.  D.  Woodbury,  assistant  district  forester,  San  Francisco,  Calif.  If  the  stump- 
high  diameters  were  used  instead  of  those'breast  high,  a  large  number  of  trees  would  be  included  in  the 
24-inch  class,  as  many  trees  measuring  22  inches  and  over,  breast  high,  would  come  within  the  24-inch  class 
if  measured  on  the  stump. 


BULLETIN    1003,   U.   S.   DEPARTMENT  OF   AGRICULTURE. 
TABLE  3. — Practical  application  of  Table  1. 


Vol- 

Trees 
24 

Aver- 

•cedt 

1 

Humps  ] 

^er  acre  < 

jquivale. 

at. 

Location. 

Area. 

per 
acre. 

inches 
and 
over. 

ameter 
stump 
high. 

24- 
inch. 

33- 
inch. 

35- 
inch. 

43- 
inch. 

49- 
inch. 

T  4  N   RISE,  sec.  19. 

Acre*. 
7 

Ed.it. 

:<:>  4<*) 

9  1 

Inches. 
48  0 

70.9 

23.6 

20.3 

12.8 

8.8 

T  9  S   R  24  E  sec  2 

16 

11)  7(K) 

»i    1'. 

34.5 

21  4 

7.1 

6.1 

T  9  N.  R  24  E,  sec.  1.  . 

16 

9  74»i 

5.5 

32.0 

19.5 

6.5 

T  8  N   R  23  E  sec.  15 

16 

11    (KM) 

4  0 

43.5 

22.0 

7.3 

4.0 

T  4  N    R  21  E  sec  32 

16 

13  112 

4.7 

43  5 

26  2 

8.7 

4.7 

TlOandllS  R25and36E 

17,  495 

12'  200 

33.0 

24.4 

8  1 

T  4  and  5  S,  R  20  and  21  E  ... 

«i,  ;•!«.):( 

6.710 

32.5 

13  4 

4.5 

T  3  and  4  S,  R  19  E 

3  820 

6  770 

33.5 

13.5 

4,5 

T  7  S   R  22  E 

300 

8  139 

33.0 

16  2 

5  4 

Volume  equivalents: 
Lumber  (board  feet).. 

500 

1  000 

1  500 

2  000 

2  500 

3  000 

3.500 

4.000 

.25 

50 

.75 

1.0 

1.25 

1.50 

1.75 

2.00 

OREGON   AND   WASHINGTON. 


Oregon. 

Washington. 

Total  area 

acres             10  000  000 

3  400,000 

Total  stand... 

board  feet       70,  000,  000,  000 

17,  000,  000,  000 

Volume  per  acre 

do                         7  000 

5,000 

Total  annual  cut  (1917)  

do....         470,488,000 

220,924,000 

Total  area  annually  cleared  (1917) 

acres                    67  212 

44,185 

Total  annual  volume  of  stumpwood  

cords..              235,244 

110,462 

Western  yellow  pine  occurs  on  about  14,000,000  acres  in  Oregon, 
practically  a  quarter  of  the  State  and  half  of  its  timbered  land.  Of 
this  area  about  10,000,000  acres  may  be  classed  as  commercial  forest, 
the  estimated  stand  amounting  to  70,000,000,000  board  feet,  or  an 
average  of  7,000  board  feet  an  acre,  interforest  waste  areas  in- 
cluded (6). 

TABLE  4—Rcprcsentatir(   irrxtern  yelloiv-vim  stands  in  Oregon. 


Location. 

Area. 

Average  number  of  trees. 

Per  cent 
of  stand. 

12-inch 
and  over. 

18-inch 
and  over. 

24-inch 
and  over. 

Near  Austin  and  Whitney 

Acres. 
258 
44 
30 
159 

25.42 
34.57 
32.00 
25.37 

18.97 
21.34 
21.23 
19.85 

13.78 
15.48 
15.10 
15.  41 

83.2 
87.3 
1       99.5 
75.2 

Near  Looldngglass  Creek  

Near  Embody  

Klamath  Lake  Section.  .  . 

Table  4  shows  average  stands  of  Oregon  yellow  pine  more  or  less 
mixed  with  other  timber.  Pure  stands  contain  a  proportionately 
greater  number  of  trees.  In  cruises  made  by  the  United  States 
(  "  "logical  Survey,  on  pure,  heavy  stands  of  yellow  pine  near  Kich- 
land,  the  average  number  of  trees  above  12  inches  on  strip  acres 
ran  from  o<)  to  !•">.  and  of  those  above  22  inches,  from  15  to  24. 
The  timber  on  tliese  strips,  ninning  about  IDjiDii  tVet  Mn  acre,  will 
yield  approximately  5  cords  of  stumpwood  an  acre. 


DISTILLATION   OF   STUMPWOOD. 


Munger  (6)  states  that  42  per  cent  of  all  butt  logs  in  Oregon  are 
fire  scarred,  and  that  25  per  cent  of  them  are  "pitched."  The 
average  diameter  of  the  "  pitchy  "  area  on  the  basal  cross  section  of 
the  log  is  14.7  inches  on  a  tally  of  1,184  butt  logs.  This  means  that 
25  per  cent  of  the  stumps  would  also  be  "  pitched "  as  the  result 
of  fire  alone  (p.  8). 

TABLE  5. — Cruises  on  the  Whitman  National  Forest,  1912-1916. 


Number  of  stumps  per  acre. 

Volume. 

Location. 

Area. 

Total 

Vol- 
ume per 

acre. 

24-inch. 

28.5- 
inch. 

33.5- 
inch. 

37-inch. 

Per 
acre. 

Ter 
area. 

Acres. 

Bd.ft. 

Bd.ft. 

Cords. 

Cords. 

T10S,  R34E,sec.l9.    .. 

640 

8,  511,  000 

13,  299 

26.59 

13.29 

8.86 

6.649 

6.649 

4,255 

T10S,  R34E,sec.33.   .. 

640 

6,  220,  000 

9,718 

19.43 

9.72 

6.48 

4.859 

4.859 

3,109 

T10S,  R34E,sec.34.   .. 

640 

7,  440,  000 

11,006 

22.00 

11.00 

7.34 

5.503 

5.503 

3.521 

T11S,  R34E,sec.  1..    .. 

640 

5,  128,  000 

8,012 

16.02 

8.01 

5.34 

4.006 

4.006 

2,564 

T11S,  R34E,  sec.  2..    .. 

640 

5,  716,  000 

8,931 

17.86 

8.93 

5.95 

4.465 

4.465 

2,857 

T11S,  R34E,sec.  11.  .. 

640 

6,992.000 

10,  925 

21.85 

10.92 

7.28 

5.462 

5.462 

3,495 

T11S,  R23E,sec.23.   .. 

640 

6,  260,  000 

9,781 

19.56 

9.78 

6.52 

4.890 

4.890 

3,130 

T12S,  R34E,  sec.  3..    .. 

640 

5,900,000 

9,287 

18.57 

9.28 

6.19 

4.643 

4.643 

2,971 

T12S,  R34E,  sec.  10.  .. 

640 

4,  776,  000 

7,448 

14.89 

7.44 

4.96 

3.724 

3.724 

2,383 

T  12S,  R  34E,  sec.  21  ... 

640 

3,  153,  000 

4,926 

9.85 

4.92 

3.28 

2.463 

2.463 

1,576 

T  12S,  R  34E,  sec.  28.  .  . 

640 

8,110,000 

12,  672 

25.36 

12.68 

8.45 

6.336 

6.336 

4,056 

Total 

7,040 

67,701  000 

33,  916 

Average 

9,474 

18.  95 

9.47 

6.32 

4.737 

4.  737 

Stand  on  56  forties  

2,240 

30,  821,  000 

13,  759 

27.52 

13.76 

9.17 

6.879 

6.879 

15,409 

Stand  on  27  sections  

17,280 

153,  565,  000 

8,886 

17.77 

8.88 

5.92 

4.443 

4.443 

76,  775 

The  total  stand  of  western  yellow  pine  for  Washington  is  12,500,- 
000,000  feet  in  private  and  State  ownership,  and  4,500,000,000  feet  in 
Government  ownership,  or  a  total  of  17,000,000,000  board  feet. 
Allowing  a  stand  of  5,000  feet  an  acre,  which  is  thought  to  be  low, 
since  Oregon  and  Washington  are  similar,  the  Washington  area  will 
be  approximately  3,400,000  acres. 

The  area  of  the  yellow-pine  land  in  the  two  States  is  approxi- 
mately 13,400,000  acres,  carrying  a  commercial  stand  of  from  5,000 
to  7,000  feet  an  acre,  or  the  equivalent  of  from  10  to  14  trees  24  inches 
on  the  stump,  which  will  yield  from  2£  to  6|  cords  of  yellow-pine 
stumpwood  an  acre. 

IDAHO,  MONTANA,  AND  UTAH. 


Idaho. 

Montana. 

Utah. 

Total  area  

acres 

10  000  000 

3  500  GOO 

(i) 

Total  stand.. 

board  feet 

5S  050  000  000 

14  OOO'OOO'OOO 

m 

Volume  per  acre  

do 

5  800 

4  000 

4  000 

Total  annual  cut  (1917)  

do 

315  009  000 

150  905  000 

4  676  000 

Total  area  annually  cleared  (1917)  
Total  annual  volume  of  stumpwood  .  .  . 

acres.. 
cords.. 

54',  311 
157,504 

'   37^726 
75,  452 

1,169 
2,338 

i  No  reliable  figures  obtainable. 


Many  large  areas  of  yellow-pine  timber  in  Idaho  are  as  good  as 
the  best  of  that  in  California  and  Oregon,  but  as  a  whole  the  stand 


8 


BULLETIN   1003,   U.   S.   DEPARTMENT  OF  AGRICULTURE. 


will  probably  average  close  to  6,000  feet  an  acre.  Conservative 
estimates  for  the  area  would  be  10,000,000  acres,  and  for  the  total 
stand,  50,000,000,000  feet. 

There  is  much  wastage  in  butt  logs,  due  to  "  pitchiness  "  resulting 
from  fire  scars  and  natural  causes.  Fires  tend  to  make  the  stumps 
more  resinous  and  to  increase  the  number  of  those  sufficiently  "  fat  " 
to  serve  for  purposes  of  distillation.  It  has  been  the  experience  of 
an  Idaho  lumber  company  that  some  of  these  "  pitchy  "  butts  occur 
in  all  the  western  yellow-pine  timber.  They  state  that  these  pitchy 
butts  are  more  prevalent  in  the  northern  section  of  Idaho,  but  that 
this  territory  and  the  Baker,  Oregon  (Blue  Mountain),  territory  pro- 


/.O ./ .2 .3 4 .J .6  .7.3.3  20J.2J4-.J.0  .7.3 .3 &?./.£'.(? .4 .30 .7.0' WM. 
/*  '  /VtfS  -2.3  4- .J~.0  7.8  .&  to./  ?.3  4-  tf.C  7.8.9  Z'Corfs 

FIG.  2. — Yellow-pine  stumpage  in  6  western  States.  A,  volume  of  tree  (thousand  board 
feet)  ;  B,  volume  of  stumpage  (cords)  ;  C,  difference  between  diameter  breast  high  and 
diameter  stump  high  (inches). 

duce  less  "  pitchy  "  lumber  than  any  other  yellow-pine  section  that 
has  come  under  their  observation. 

From  this  it  would  seem  that  the  question  of  "  pitchy  "  butts  is 
important,  and  should  not  be  ignored  by  those  who  attempt  to  de- 
termine the  amount  of  resinous  wood  to  be  obtained  from  any  lo- 
cality. Since  25  per  cent  of  the  butt  logs  from  the  Blue  Mountain 
region  bear  more  or  less  pitch,  and  a  wastage  in  "  pitchy  "  butts 
trimmed  off  of  from  4  to  5  cords  a  day  is  reported  by  one  company, 
this  constitutes  a  very  important  source  of  valuable  wood  for  dis- 
tillation purposes.  Samples  sent  to  the  University  of  Idaho  com- 
pared favorably  with  the  best  stumpwood  in  yield  of  products.  The 


DISTILLATION   OF   STUMPWOOD. 


9 


mill  which  submitted  the  samples  was  compelled  to  sell  more  than 
a  million  board  feet  of  yellow-pine  lumber  at  a  loss,  because  of  the 
amount  of  "  pitchy  "  lumber  in  the  butt  logs.  Inspection  by  one  of  the 
writers  showed  a  large  amount  of  this  wood  to  be  suitable  for  distil- 
lation. 

TABLE  6. — Average  volume  of  loestern  yellow  pine  and  reduction  factors  for 
various  volumes  and  diameters  of  trees  and  stumps  (Idaho  and  Montana). 


Diameter. 

Average  volume. 

Reduc- 

Reduc- 

for 
different 

Breast 
high. 

breast 
height 
to  stump 
height. 

Stump 
high.i 

Of  tree. 

Of  stump. 

volumes 
and 
diame- 
ters. 

Inches. 

Inches. 

Inches. 

Bd.ft. 

Cords. 

22 

2.0 

24.0 

500 

0.25 

1.0 

23 

2.0 

25.0 

550 

24 

2.0 

26.0 

600 

25 

2.0 

27.0 

675 

26 

2.0 

28.0 

750 

0.375 

1.5 

27 

2.0 

29.0 

850 

28 

2.0 

30.0 

,000 

0.50 

2.0 

29 

2.5 

31.5 

,150 

30 

2.5 

32.5 

,250 

0.625 

2.5 

31 

2.5 

33.5 

375 

32 

2.5 

34.5 

^500 

0.75 

3.0 

33 

2.5 

35.5 

.625 

34 

3.0 

37.5 

1,750 

0.875 

3.5 

35 

3.0 

38.5 

1,875 

36 

3.0 

39.0 

2,000 

1.00 

4.0. 

37 

3.0 

40.0 

2,250 

1.125 

4.5 

38 

3.0 

41.0 

2,400 

38.5 

3.5 

42.0 

2.500 

1.25 

5.0 

39 

3.5 

42.5 

2,600 

40 

3.5 

43.5 

2,700 

40.5 

3.5 

44.0 

2  850 

42 

3.5 

45.5 

3,000 

1.50 

6.0 

1  See  also  Figure  2. 

TABLE  7. — Cruise  of  160  acres  of  western  yellow  pine  in  Boise  County,  Idaho  (all 

trees  calipered). 


Average  diame- 
ter. 

Num- 
ber 

Ptumpwood. 

Num- 

stumps 

Aver- 

ber 

per  acre 

Eauiv- 

age 

24-inch 

equiva- 

alent 

Location. 

stand 

stumps 

lent, 

used  in 

per 
acre. 

Breast 
high. 

Stump 
high.i 

per  acre 
eauiva- 
lent. 

based 
on  aver- 
age 

Per 
acre. 

Per 
section. 

reduc- 
tion. 

diame- 

ter. 

Bd.ft. 

Inches. 

Inches. 

Cords. 

Cords. 

Bd.ft. 

T  6N,  R  5E.  sec.  8  NW  NW 

14  693 

25  5 

27  5 

29  38 

20  55 

7  34 

293  6 

715 

T  7N.  R  4E,  sec.  35  SE  NE  .  .  . 

15,144 

27.4 

29.4 

30.29 

16.83 

7.'  57 

302.8 

900 

T  7N,  R  4E,  sec.  35  NE  NE. 

13,866 

25.5 

27.5 

27  73 

19  40 

6  93 

277  2 

715 

T  7N,  R  4E,  sec.  35  NE  SE  . 

15  783 

26.7 

28  7 

31  57 

18  70 

7  89 

315  6 

800 

Average,  4  forties  

14,896 

26.27 

28.27 

29.74 

19.12 

7.681 

2189.2 

782.5 

1  From  Table  6. 

2  Total  number  of  cords  of  stumpwood  for  entire  area. 


10  BULLETIN   1003,   U.   S.  DEPARTMENT   OF  AGRICULTURE. 

TABLE  8. — Cruises  of  478.85  acres  of  western  yellow  pine  in  Latah  County,  Idalw. 


Average  diame- 
ter. 

Num- 
ber 

Stumpwood. 

Num- 

stumps 

Aver- 
age 

ber 

21-inch 

per  acre 
equiva- 

Equiv- 
alent 

Location. 

stand 

stumps 

lent, 

used  in 

per 
acre. 

Breast 
high. 

Stump 
high.i 

per  acre 
equiva- 
Fent. 

based 
on  aver- 
age 

Per 

acre. 

Per 
area. 

red  uc- 
tion. 

diame- 

ter. 

Bd.ft. 

Inches. 

Inches. 

Cords. 

Cords. 

Bd.ft. 

T  39N  R  1W  sec  2  lot  7 

R  7.10 

29 

31.5 

17.50 

7.60 

4.18 

162.  39 

1,150 

T39N,  R  lW,scc.  9  SE  NW  10,625 

34 

37.5 

21.25 

6.07 

5.12 

204.80 

1,750 

T39N.  R  IW.sec.  23  NE  SW...          '    8750 

34          37.  5 

17.50 

5.00 

4.19 

167.60 

1,750 

T  40N  R  IW.sec.  23  NE  SW               i    7500 

28          30-0 

13.00 

7.50 

3.75 

150.00 

1,000 

T40N,  R  IW.soc.  24NENE...         .10,500 

26 

28.0 

21.00 

14.00 

5.25 

210.00 

750 

T40N,  R  IW.sec.  24  NESE..                  8925 

26 

28.0 

17.86 

11.89 

4.46 

17v  in 

750 

T40N,R2W,sec.  14SENW....          n.x7:> 

28.0 

23.75 

15.83 

5.93 

237.20 

750 

T  42N   R  3W  sec  36  NE  NW                 17  500 

29          31.5 

35.00 

15.30 

8.75 

350.00 

,150 

T  41N,  R  4W,sec.  29  SE  SE...                9,625 

34           37.  5 

19.25 

5.50 

4.81 

192.40 

,750 

T  41N,  R  4W,  sec.  31  SE  NW  10.000 

32          34.  5 

20.00 

6.67 

5.00 

200.00 

,500 

T  42N,  R  4W,  sec.  33  SE  N  W  .  .  . 

11,500 

30          32.  5 

23.00 

9.20 

5.57 

222.80 

.-'.-(> 

T  42N,  R  5W,  sec.  36  SW  SE  .. 

11,000 

29.  5       32.  0 

22.00 

9.17 

5.50 

220.00 

,200 

Average,  per  forty 

10,545 

29.8 

32.38 

21.09 

9.48 

5.21 

207.97 

1,229 

1  From  Table  6. 


TABLE  9. — Recapitulation  of  cruixes. 


Location. 

Area 
cruised. 

Total  stand- 

Volume 
per  acre. 

Number 
24-inch 
trees  per 
acre 
equiva- 
lent. 

Stumpwood. 

Per  acre. 

Per  area. 

T  39N,  R  1W,  B  M... 

Acres. 
4,840 
10,291 
7,380 
4,733 
6,147 
4,240 

Bd.ft. 
24.967,000 
52,218,000 
69,  125,  000 
36,  894,  000 
37,  525,  000 
25,680,000 

Bd.ft. 
5,158 
5,074 
9,366 
7,729 
6,098 
6,056 

10.32 
10.15 
18.73 
15.46 
12.21 
12.06 

Cards. 
2.57 
2.53 
4.68 
3.86 
3.04 
3.02 

Cords. 
12,438 
26,136 
34,538 
18,423 
18,686 
12,804 

T  40N,  R  1W,  B  M 

T  40N,  R  2W   B  M 

T  42N,  R  3W.B  M... 

T  41N,  R  4W,  B  M 

T  42N,  R  4W   B  M 

Total 

37,671 

246,409,000 

123,  025 

Average 

6,580 

13.15 

3.28 

1  The  estimates  include  only  yellow  pine,  which  constituted  but  53.34  per  cent  of  the  entire  stand.    A 
pure  stand  would  be  heavier. 

In  all  tables  a  slight  discrepancy  will  be  noticed  between  the  total 
number  of  cords  of  stumpwood,  when  added  and  when  computed. 
This  is  due  to  the  dropping  of  decimals  and  the  using  of  even  numbers 
only  in  cruise  tables. 

The  average  stand  over  large  areas  of  yellow  pine  in  Idaho  is  from 
5,000  to  15,000  board  feet  an  acre,  or  from  10  to  30  trees,  '24  inches  in 
diameter  on  the  stump,  the  volume  of  stumpwood  running  from  *2\  to 
8  cords  an  acre.  For  more  open  stands  the  number  of  Mumps  will 
be  less,  but  such  stumps  are  generally  larger  and  consequently  more 
resinous.  Therefore  the  volume  of  "  pitchy"  wood  will  be  consider- 
able, but  can  be  determined  only  by  a  field  survey  of  each  region. 


DISTILLATION   OF  STUMPWOOD. 


11 


TABLE  10. — Cruises  of  3,200  acres  of  western  yellow  pine  in  Boise  County, 

Idaho.1 


Location. 

Av- 
erage 
per  acre 
for  sec- 
tion. 

Average  diam- 
eter. 

No.  24- 
inch 
stumps 
per  acre 
equiv- 
alent. 

No. 
stumps 
per  acre 
equiv- 
alent, 
based 
on  av- 
erage 
diam- 
eter. 

Stump  wood. 

Diam- 
eter 
equiv- 
alent, 
used  in 
r^duc- 
tion. 

Breast 
high. 

Stump 
high. 

Per 
acre. 

Per  sec- 
tion. 

T   7  N   R  5  E,  sec.  12 

Bd.ft. 
9,945 
10,960 
15,  336 
18,  814 
10,  453 

Inches. 
29.2 
25.5 
28.5 
31.0 
22.3 

Inches. 
31.7 
27.5 
30.5 
35.5 
25.3 

19.90 
21.92 
30.66 
37.63 
20.90 

8.50 
15.10 
14.60 
13.68 
18.66 

Cords. 
4.97 
5.19 
7.66 
9.40 
5.22 

Cords. 
3,  180.  8 
3,321.6 
4,902.4 
6,016.0 
3,340.8 

Bd.ft. 
1,170 
715 
1,050 
1,375 
560 

T    7  N.  R  4  E.  see.  35  

T  14  N    R  5  E,  sec.  30 

T  14  N.  R  3  E,  sec.  12  

T  13  N,  R  5  E,  sec.  7  

Average  

13,  101 

27.3 

29.7 

26.20 

14.11 

6.51 

220,761.2 

974 

1  Only  yellow  pine  which  is  practically  all  over  22  inches  diameter,  breast  high,  or  24  inches  diameter, 
stump  high,  is  included. 

2  Total  number  of  cords  of  stumpwood  for  the  entire  area. 

TABLE  11. — Recapitulation  of  cruises  of  509,670  acres  of  pure  western  yellow 

pine. 


Location. 

Area. 

Diam- 
eter, 
stump 
high. 

No.  trees. 

Av- 
erage 
diam- 
eter, 
stump 
high. 

Av- 
erage 
No. 
bd.ft. 
per 
tree. 

No. 
bd.ft. 
per 
acre. 

Av- 
erage 
no.  24- 
inch 
stumps 
per  acre 
equiv- 
alent. 

No. 

stumps 
per 
acre 
of  av- 
erage 
diam- 
eter. • 

Av- 
erage 
no. 
cords 
stump- 
wood 
per 
acre. 

Total. 

Av- 
erage 
per 
acre. 

Kaibab  National  For- 
est 

Acres. 
300,000 

Inches. 
13-16 
18-22 
24+ 

3,258,000 
2,400,000 
2,220,000 

11.76 

8.00 
6.74 

Inches. 
15.00 
20.18 
28.70 

145 
330 
820 

1,705 
2,600 
5,527 

Total  

11.05 

6.74 

4.0 

8,148,000 

298,  908 
167,808 
403,  788 

25.50 

9,838 

South  Payette  River, 
Payette    National 
Forest  

— 

— 

_•__-!'—•   •_•'- 

52,  440 

13-16 
18-22 

24  + 

5.7 
3.2 

7.7 

14.8 
21.1 

28.2 

140 
410 
770 

798 
1,312 
5,929 

Total  

11.86 

7.50 

3.62 

870,504 

16.6 

8,039 

Middle  Fork,  Payette 
National  Forest  

Total  

58,690 

13-16 

I£r22 

24+ 

297,558 
190,742 
434,306 

5.07 
3.25 
7.40 

15.38 
20.50 
29.50 

165 

355 
900 

786 
1,154 
6,660 

= 

= 

-.   -. 



13.32 

7.40 

3.9 

922,606 

15.72 

8,600 

Weiser  National  For- 
est   

98,540 

13-16 

18-22 
24+ 

451,367 
274,926 
675,984 

4.68 
2.79 
6.86 

14.29 
20.04 
29.00 

120 
325 
850 

562 
907 
5,831 

^^ 

Total  

11.66 

6.86 

3.36 

1,402,277 

14.33 

7,300 

All  commercial  stands  of  yellow  pine  in  Montana  are  confined  to 
the  western  part  of  the  State.  Much  of  the  timber  is  of  about  the 
same  grade  as  that  found  in  Idaho,  but  the  stand  usually  is  lighter 
and  the  timber  a  little  shorter,  and  as  a  rule  it  contains  a  slightly 
smaller  percentage  of  "  pitchy  "  stumps.  Many  large  areas  in  the 


12 


nr 1. 1. 1. TIX  loon,  r.  s.  DKPAKT.MKXT  OF  AGRICULTURE. 


State  carry  heavy  stands  of  from  5,000  to  7,000  board  feet,  and  in 
time  the  resinous  wood  may  lv  handled  to  commercial  advantage. 
The  working  tables  for  Idaho  can  readily  be  applied  in  efforts  to 
determine  the  volume  of  stumpwood  on  any  area.  The  average  stand 
to  the  acre  for  the  entire  commercial  yellow-pine  region  of  the  State 
may  be  taken  to  be  4,000  board  feet. 

The  yellow-pine  region  of  Utah  is  scattered  over  an  extensive  area, 
and  until  a  more  detailed  survey  is  made  it  will  be  impossible  to 
state  the  value  of  the  stumpwood  for  distillation  purposes.  As  a 
rule,  it  is  far  from  transportation  facilities  and  markets,  so  that  for 
the  present  it  may  be  considered  as  having  but  a  slight  bearing  on 
the  distillation  problem.  It  has  been  assumed  that  the  average  stand 
from  which  the  1917  lumber  cut  was  obtained  carried  3,000  board 
feet  an  acre.  In  all  probability  it  was  decidedly  higher,  as  the  best 
stands  are  generally  being  cut  first.  This  would  reduce  the  number 
of  acres  a'nnually  cleared,  but  would  not  affect  the  volume  of  stump- 
wood. 

COLORADO,    SOUTH    DAKOTA,   AND   WYOMING. 


Colorado. 

South  Dakota. 

Wyoming. 

Total  area  J 

acres 

916,415 

707,000 

8,000 

Total  stand  > 

board  feet 

1  618  614  000 

2  873,000  000 

23  500  000 

Volume  per  acre  

do.... 

1,766 

4,063 

2,937 

Total  annual  cut  (1917)  

do 

35,328  000 

29,045,000 

3  678  000 

Total  area  annually  cleared  (1917)  
Total  annual  volume  of  stumpwood  

acres.. 
.  t  cords.. 

20,004 
17,664 

7,149 
14,522 

1,252 
1,839 

i  From  Forest  Service  records. 

The  commercial  stands  of  yellow  pine  in  Colorado  are  confined 
in  a  large  measure  to  the  national  forests.  They  are  scattered  over 
nearly  a  million  acres,  but  the  volume  to  the  acre  is  lower  than 
that  in  any  other  State.  It  is  not  probable  that  any  value  may  be 
derived  from  this  stumpland  in  the  way  of  distillation  products. 

The  chief  yellow-pine  area  in  South  Dakota  is  located  in  the 
Black  Hills  region.  The  average  stand  for  the  707,000  acres  is 
4,063  board  feet  an  acre,  making  the  volume  of  stumpwood  about 
two  cords  an  acre,  which  is  thought  to  be  low  for  distillation  pur- 
poses, as  the  wood  is  not  especially  resinous. 

The  stand  in  Wyoming  is  so  small  as  to  be  entirely  negligible  for 
the  purposes  of  distillation. 

SUMMARY. 

This  brief  survey  shows  that  the  quantity  of  stumpwood  is  enor- 
mous and  that  the  problem  of  handling  the  cut-over  areas  is  of  first 
importance.  It  is  known,  however,  that  not  all  of  these  stumps 
arc  sufficiently  resinous  for  profitable  distillation,  under  present 
conditions. 


DISTILLATION    OF   STUMPWOOD.  13 

TABLE  12. — Annual  lumber  cut  of  western  yellow  pine  in  the  United  States  (9). 


Volume. 

State. 

1914 

1915 

1916 

19171 

Stumpwood  2 

California 

Bd.ft. 
409  953  000 

Bd.ft. 
389  991  000 

Bd.ft. 
494  973  000 

Bd.ft. 
478  565  000 

Cords. 
239  282 

Oregon         ... 

210.  438.  000 

189,  203,  000 

399,  102,  000 

470,  488,  000 

235,244 

Washington 

175.  426.  000 

148,789  000 

188  215,000 

220,924  000 

110  462 

Idaho  

159,  839,  000 

201,  858,  000 

240,  160,  000 

315,009,000 

157,504 

Montana  

134,  568,  000 

118,  920,  000 

138,  206,  000 

150,  905,  000 

75,  452 

Arizona 

78.667  000 

75,  843,  000 

92  133  000 

78  147  022 

39,  074 

New  Mexico  

54,  728,  000 

61,466,000 

72,004,000 

76,  149,  793 

38,074 

Colorado.  .  .                 

65,117,000 

37,  241,  000 

27,  848,  000 

35,  328,  000 

17,664 

South  Dakota 

18,744  000 

22  457  000 

25  466  000 

29  045  000 

14,  522 

All  other  

19,  885,  000 

6,476,000 

6,880,000 

8,354,000 

4,177 

Total 

1  327  366  000 

1  252  244  000 

1  684  987  000 

1  862  914  815 

931  455 

1  From  records  of  the  district  foresters. 

2  For  1917  only. 

SUMMARY  OF  TABLE  12. 

Total  volume,  1914-1917,  inclusive (board  feet). .  6, 127, 511, 815 

Total  area  equivalent  cleared,  1914-1917,  inclusive,  assuming  5,000  feet 

as  average  per  acre .' (acres) . .  1, 225, 502 

Total  stumpwood,  1914-1917,  inclusive , (cords) . .  3, 063, 755 

If  the  areas  are  not  agricultural  in  character,  they  should  be 
allowed  to  reforest.  In  this  case  the  land-clearing  problem  is  not 
so  important,  although  the  stumps  should  be  utilized,  if  it  is  economi- 
cally possible  to  do  so.  Table  12  shows  that  for  the  entire  area  of 
western  yellow-pine  land  the  average  volume  of  stumpwood  is  2.5 
cords  an  acre,  or  100  cords  for  every  40-acre  tract.  Probably  half 
of  this  land  carries  double  this  amount  of  stumpwood.  Be  that  as  it 
may,  it  is  certain  that  many  thousands  of  cords  of  stumpwood  must 
be  removed  before  those  who  desire  to  make  homes  on  the  splendid 
yellow-pine  lands,  some  of  which  are  known  to  be  among  the  best 
remaining  lands  obtainable  for  agriculture,  can  bring  them  into  the 
proper  state  of  cultivation  and  production. 

PURPOSE  OF  INVESTIGATION. 

In  January,  1914,  the  Bureau  of  Chemistry,  United  States  Depart- 
ment of  Agriculture,  in  cooperation  with  the  Department  of  For- 
estry of  the  University  of  Idaho,  at  Moscow,  Idaho,  began  a  study 
of  the  destructive  distillation  of  logging  and  land-clearing  waste  in 
the  State  of  Idaho,  particularly  of  the  yellow-pine  stumps  of  that 
region.  These  investigations  were  instituted  with  the  twofold  pur- 
pose of  ascertaining  the  feasibility  of  more  effectively  utilizing  the 
timber  resources  of  the  Northwest  and  of  reducing  the  net  cost  of 
clearing  cut-over  lands  for  agricultural  purposes  by  the  recovery  of 
commercially  valuable  products  from  the  stumps.  The  work  resolved 
itself  into  determining  (a)  the  nature,  amount,  and  probable  value 
of  certain  by-products  obtained  in  clearing  the  land  of  stumps  by 


14  BTLLKTIX    1003,    U.   S.   DEPARTMENT    OP    A<  iIM(  TLTURE. 

burning  and  the  practicability  of  recovering  these  products  by  this 
method,  and  (b)  the  yield  and  value  of  products  obtainable  from 
yellow-pine  stumpwood  throughout  the  State  when  subjected  to  re- 
tort distillation. 

The  chief  aim  of  the  cooperative  work  was  to  determine  the  value 
for  distillation  purposes  of  western  yellow-pine  stumps  and  such 
other  logging  or  land-clearing  waste  in  the  State  of  Icttiho  as  might 
lend  itself  to  the  treatment.  The  abundance  of  yellow-pine  waste 
is  readily  inferred  from  the  volume  of  such  lumber  sent  to  market 
from  mills  throughout  the  State,  and  the  relative  abundance  of  yel- 
low-pine stumps  in  any  section  can  be  ascertained  from  timber-cruise 
records,  supplemented  by  the  proper  volume  tables.  The  quality  of 
the  stumps  with  respect  to  their  resin  content,  on  which  depends 
their  value  for  distillation  purposes,  however,  can  not  be  determined 
from  such  field  or  timber-cruise  data.  The  results  of  careful  field 
inspections  have  led  to  the  conclusion  that  much  of  the  western  yel- 
low pine  is  of  the  relatively  nonresinous  or  "bull  pine"  variety. 
Even  the  more  resinous  yellow-pine  stumps  varied  so  widely  in  their 
resin  content  that  it  soon  became  apparent  that  field  investigations 
were  indispensable  to  a  proper  knowledge  of  the  proportion  in  which 
the  various  grades  of  stumps  occur  in  the  regions  from  which  samples 
were  collected.  A  knowledge  of  the  conditions  in  the  yellow-pine 
belt  of  the  Atlantic  and  Gulf  States  made  this  all  the  more  impera- 
tive, for  the  reason  that  the  apparent  preponderance  of  the  lower 
grade  of  stumps  clearly  indicated  that  the  profitable  utilization  by 
distillation  of  all  yellow-pine  stumps  would  be  found  impracticable, 
and  that  success  in  utilizing  any  of  them  would  depend  on  a  proper 
selection  of  material  to  be  treated. 

From  an  agricultural  standpoint  the  object  of  the  work  was  to 
determine  the  practicability  of  reducing  cut-over  land  clearing  costs 
through  recovery  of  by-products  from  the  stumps.  The  extent  to 
which  distillation  products  from  the  stumps  can  be  made  to  defray 
the  cost  of  clearing  such  land  obviously  depends,  among  other  things, 
on  the  total  number  of  stumps  to  the  acre,  the  number  of  these  stumps 
suited  to  distillation  purposes,  the  yield  and  value  of  the  by-products, 
and,  finally,  the  cost  of  recovering  these  by-products  from  the  stumps 
to  be  treated.  The  first  of  these  probably  can  be  fairly  well  estab- 
lished from  timber-cruise  records  for  regions  in  which  such  data  are 
available;  the  second  is  a  combined  field  and  laboratory  problem;  the 
third  a  laboratory  and  trade  inquiry  problem ;  and  the  fourth  a  field 
and  chemical  engineering  problem.  The  work  accordingly  resolved 
itself  into  an  investigation  involving  each  of  these  closely  related 
problems. 


DISTILLATION    OF   STUMPWOOD.  15 

TAKING  SAMPLES. 

In  the  spring  of  1914,  samples,  with  the  attendant  field  data,  were 
obtained  from  four  acres  in  different  parts  of  the  State  typical  of 
the  regions  they  were  selected  to  represent,  namely:  (a)  Cut-over 
land  of  a  lumber  company  in  Latah  County,  hereafter  referred  to  as 
the  Potlatch-Deary  region;  (l>)  the  Coeur  d'Alene  and  Hay  den  Lake 
region;  (c)  the  South  Idaho  or  Boise-Payette  region;  and  (d)  the 
Craig  Mountain  or  Winchester  region. 

In  these  field-sampling  operations  a  rapid  reconnaissance  trip  was 
made  to  get  a  general  idea  as  to  the  abundance  and  apparent  quality 
of  the  stumps  in  a  region.  On  the  basis  of  such  knowledge  an  area 
considered  representative  of  the  district  was  selected,  from  which 
samples  representing  the  different  qualities  of  stumps,  together  with 
data  for  an  estimate  of  their  relative  abundance  and  number  per 
acre,  wrere  taken. 

In  the  beginning  the  stumps  were  arbitrarily  classed  as  "  rich " 
when  the  top  showed  a  marked  resinous  exudation,  or,  if  burned  over, 
revealed  decidedly  resinous  wood  when  cut  into  with  an  axe,  as 
"medium"  when  it  showed  but  little  of  such  exudation,  and  as 
"poor"  when,  although  apparently  sound,  it  was  devoid  of  any 
resinous  exudation.  All  stumps  containing  little  if  any  resinous 
wood  are  classed  as  "  bull  pine,"  despite  the  fact  that  this  term  is 
usually  limited  to  the  western  yellow  pine  less  than  24  inches  across 
the  stump. 

Selected  stumps  of  each  class  were  removed  by  blasting,  and  only 
enough  of  their  heartwood  was  taken  to  make,  with  wood  from  other 
stumps  of  the  same  quality,  a  cord  sample  of  that  class.  This  cord, 
or  a  smaller  sample  selected  from  this  measured  cord,  was  then 
shipped  to  Moscow  for  the  experimental  work. 

In  all  cases  the  sapwood  was  split  off  and  rejected;  hence  the  re- 
sults obtained  in  this  investigation  do  not  show  what  can  be  ob- 
tained from  the  whole  stump  of  each  quality,  but  only  from  the 
resinous  heartwood.  Because  the  western  yellow-pine  stumps  ordi- 
narily contained  so  little  heartwood  (on  an  average  about  50  per 
cent),  stumps  under  24  inches  were  considered  only  when  they  con- 
tained larger  proportions  of  the  resinous  heartwood.  Such  stumps, 
in  later  years,  should  the  sapwood  rot  off  while  the  heartwood  re- 
mained sound  and  resinous,  would  then  be  practically  100  per  cent 
resinous,  but,  of  course,  would  yield  a  much  smaller  quantity  of 
total  wood. 

Distinction  between  "  yellow  pine  "  and  "  bull  pine" — The  term 
"  yellow  pine  "  is  here  used  to  designate  such  members  of  the  Pinus 
ponderosa  group  as  contain  an  appreciable  portion  of  relatively  resin- 


16  BULLETIN  1003,   U.   S.   DEPARTMENT  OF  AGRICULTURE. 

ous,  dark-colored  heartwood,  compared  to  the  sap  wood  layer.  "  Bull 
pine,"  although  often  large,  has  relatively  no  such  high  proportion 
of  the  richer  resinous  heartwood.  Botanically,  the  "bull  pine'1  is 
considered  to  belong  also  to  the  Pinus  ponderosa,  or  western  yellow- 
pine  group,  appearing  to  differ  from  the  "yellow  pine"  only  in 
being  a  less  mature  or  more  rapidly  developed  tree.  Whatever  may 
be  the  cause,  the  important  fact  remains  that  "  bull-pine  "  stumps, 
aside  from  their  content  of  what  appears  to  be  sapwood,  are  all  but 
devoid  of  resinous  matter  and  are  utterly  worthless  for  the  recovery 
of  turpentine  or  other  distillation  products  (Table  14).  "  Bull-pine  " 
stumps,  irrespective  of  their  size,  therefore,  are  not  included  in  the 
number  of  yellow-pine  stumps  to  the  acre  in  a  given  area  or  section, 
which  makes  it  highly  important  to  remember  that  no  such  distinc- 
tion between  these  classes  of  stumpage  is  made  by  timber  cruisers. 

POTLATCH-DEARY   REGION. 

The  southwest  quarter  of  the  southeast  quarter  of  section  15,  town- 
ship 40  north,  range  2  west,  readily  accessible  and  fairly  represen- 
tative of  the  number,  size,  and  quality  of  stumps  to  the  acre  of 
yellow-pine  land  in  the  Potlatch- Deary  section  of  the  State,  had  had  a 
yellow-pine  stand  of  395,000  board  feet  a  "  forty,"  averaging  500 
feet  a  tree.  The  average  yellow-pine  stand  for  the  township  was 
234,000  board  feet  to  40  acres. 

The  stumps  were  taken  from  a  south  slope,  a  ridge,  and  its  adjacent 
lowland.  The  trees  had  been  felled  six  or  seven  years  before,  and 
the  stumps  were  generally  found  with  all  the  bark.  A  few  burnt- 
over  stumps,  of  which  the  bark  and  sapwood  had  been  destroyed, 
from  trees  said  to  have  been  dead  when  cut  and  in  some  cases  felled 
for  fuel  wood  13  years  earlier,  were  included.  Ten  stumps  of  each 
class  were  blown  out  and  enough  of  the  heartwood  from  each  stump 
taken  to  make  up  a  cord  sample  of  each  class.  The  stumps  were  re- 
moved by  blasting  with  both  40  per  cent  and  20  per  cent  dynamite. 
Few  of  the  stumps  were  removed  entirely  by  the  blast,  most  of  them 
being  either  split  through  the  middle,  with  only  part  of  the  stump 
thrown  out,  or  left  standing  in  a  shattered  condition.  It  was  neces- 
sary, therefore,  to  employ  a  team  of  horses  to  remove  enough  of  such 
shattered  stumps  to  obtain  a  sufficient  portion  of  each  for  the  samples. 

All  of  the  heartwood  of  the  first  few  stumps  shot  out  was  removed 
and  split  to  approximately  cordwood  size,  and  a  sample  taken  from 
each  stump  thus  entirely  reduced.  The  labor  cost,  estimated  at  from 
$4  to  $5  a  cord,  made  it  so  expensive,  however,  that  only  a  portion 
of  each  stump  sufficient  to  obtain  enough  for  a  sample  was  reduced. 
The  diameters  of  the  ten  "  rich  "  stumps  varied  from  24  to  40  inches, 
with  an  average  of  32  inches:  those  of  "medium"  quality,  from  26 
to  36  inches,  with  an  average  of  30  inches;  and  the  "poor"  stumps, 


DISTILLATION    OF   STUMPWOOD.  17 

from  24  to  36  inches  with  an  average  of  28  inches.     The  cost  of 
shooting  the  30  stumps  was  as  follows  (spring,  1914)  : 

Two  men,  2^  days,  at  $2.50  a  day  of  10  hours $12.  50 

50  pounds  of  20  per  cent  dynamite 7.50 

165  pounds  of  40  per  cent  dynamite 28.  05 

Fuses  and  caps 2.  75 

Total   50. 80 

Splitting  the  30  stumps  so  as  to  obtain  from  each  a  sufficient  por- 
tion for  the  sample  required  the  work  of  3  men  for  3  days,  which, 
at  $2.50  a  10-hour  day,  amounted  to  $22.50.  The  cost  of  gathering 
and  hauling  the  3  cords  of  wood,  requiring  the  services  of  2  men  and 
a  2-horse  team  for  three-fourths  of  a  day  at  $7.50  a  day,  was  $5.62. 
If  special  stumping  powder,  selling  for  $12.50  a  100  pounds  at  that 
time,  had  been  used,  the  powder  cost  could  perhaps  have  been  reduced 
by  20  per  cent,  or  to  $30  for  the  30  stumps.  The  labor  cost  of  plac- 
ing the  shot  holes  and  shooting  the  stumps  could  probably  be  reduced 
on  a  steady  job.  Against  this  it  should  be  said  that  to  have  removed 
all  the  stumps  completely  would  have  required  the  time  of  a  man 
and  a  team  of  horses  for  an  additional  day,  as  well  as  extra  powder, 
fuses,  and  caps.  The  labor  cost  of  shooting  the  30  stumps  should 
accordingly  be  left  at  $12.50.  To  have  split  the  stumps  completely 
so  as  to  recover  all  the  heartwood  and  permit  the  handling  of  the 
pieces  by  2  men  would  have  taken  the  3  men  3  days  more,  making 
the  cost  of  splitting  the  30  stumps  $45.  On  a  steady  job  with  men 
accustomed  to  the  work,  provided  with  tools  or  equipment  that 
experience  would  suggest,  this  item  possibly  could  be  reduced  by 
at  least  50  per  cent,  or,  in  this  case,  to  $22.50.  On  the  basis  of  an 
average  of  50  per  cent  heartwood  in  the  stumps,  it  is  estimated  that 
at  least  3  stumps  are  required  to  make  a  cord  of  wood,  or  about  10 
cords  from  the  30  stumps.  To  gather  up,  haul,  and  load  this  on  the 
car  would  cost  10/3  times  $5.62,  or  $18.73.  Summing  up  on  this 
•basis,  the  cost  of  these  10  cords  of  wood  loaded  on  the  car  after  a 
1-mile  haul  is : 

Powder,  fuse,  and  caps $30.  00 

Shooting    12. 50 

Splitting    22. 50 

Gathering    and    hauling 18.  73 


Total 83.  73 

Cost   u   cord . 8.  37 

Liberal  allowances  have  been  made  in  the  items  on  which  the  cost 
of  this  yellow-pine  stumpwood  depends,  and  the  cost  a  cord  is  con- 
fidently believed  to  be  a  minimum  one.    A  material  reduction  of  this 
figure  need  be  expected  only  from  the  use  of  hitherto  undeveloped 
60953°— 21 2 


18  BULLETIN   1003,   U.   S.  DEPARTMENT  OF  AGRICULTURE. 

land-clearing  methods,  from  a  failure  on  the  part  of  the  farmer  to 
charge  the  value  of  his  time  and  equipment  in  shooting,  reducing, 
and  hauling  the  stumps  against  the  cost  of  the  wood  so  delivered,  or 
from  a  decided  reduction  in  the  selling  price  of  explosives  or  in 
labor. 

The  conclusions  based  on  this  method  of  sampling  were  subse- 
quently checked  by  removing  all  the  yellow-pine  stumps  on  a  typical 
acre,  taken  to  represent  a  good  stand  of  large  yellow  pine  in  the 
Potlatch- Deary  yellow-pine  region,  in  the  southwest  quarter  of  the 
southeast  quarter  of  section  36,  township  42  north,  range  5  west. 
The  yellow-pine  stand  on  this  "  forty  "  was  540,000  board  feet,  of 
which  240,000  board  feet  were  from  trees  averaging  TOO  feet  a  tree, 
and  300,000  board  feet  from  trees  averaging  2,500  feet  a  tree.  This 
figures  out  to  a  stand  of  9  of  the  smaller  trees  containing  a  total  of 
6,000  feet  and  3  large  trees  containing  a  total  of  7,500  feet,  or  a 
total  of  13,500  feet  an  acre.  Of  the  12  yellow-pine  stumps  on  this 
chosen  acre,  9  averaged  30  inches  and  3  averaged  45  inches  in  di- 
ameter. The  proportion  and  quality  of  the  heartwood  were  so 
markedly  different  in  the  large  stumps,  as  compared  with  that  in  the 
small  stumps,  that  the  woods  from  the  large  and  small  stumps  were 
collected  separately  as  two  samples,  and  are  hereafter  referred  to 
as  "  large  "  and  "  small "  yellow-pine  stumps,  Potlatch,  Idaho. 

A  sample  taken  from  so-called  "  rich  butts,"  "  tops,"  etc.,  was 
collected  throughout  the  area  from  which  the  stumps  at  Deary  were 
obtained,  where  a  large  amount  of  this  material  is  available  in  the 
form  of  dead  standing  trees  and  windfalls.  Judged  by  its  appear- 
ance, little,  if  any,  of  it  is  rich  in  resinous  matter.  Hence  one  sample 
only,  designated  in  the  tables  as  "  dead,  down  wood,"  was  selected 
from  the  richer  material  of  this  class. 

COEUR  D'ALENE  AND  HAYDEN  LAKE  REGION. 

The  Coeur  d'Alene  and  Hayden  Lake  region,  taken  as  being  rep- 
resentative of  cut-over  yellow-pine  lands  in  northern  Idaho,  proved 
to  be  an  unwise  selection,  as  a  larger  proportion  of  "  bull  pine  "  or 
nonresinous  material  was  found  there  than  in  the  Pend  d'Oreille 
River  country  farther  to  the  north.  It  should  be  considered  typical 
rather  of  the  yellow  pine  in  the  territory  within  a  50-mile  radius  of 
Spokane.  Two  yellow-pine  samples  were  taken,  one  on  a  ranch  some 
2  miles  northwest  of  Hayden  Lake  towards  Garwood,  the  other  from 
the  Mica  Bay  section  of  Coeur  d'Alene  Lake.  The  first  was  repre- 
sentative of  the  average  quality  of  yellow-pine  stumps  proper  in  the 
Hayden  Lake  region,  few,  if  any,  of  which  showed  resinous  exuda- 
tion, and  approximated  20  to  35  an  acre  in  the  closest  yellow-pine 
stand  of  this  region,  which  had  been  cut  over  a  few  years  before. 


DISTILLATION   OF   STUMP  WOOD.  19 

The  sample  collected  at  Coeur  d'Alene  Lake  was  from  "  rich  "  stumps 
on  a  20  to  30  acre  tract  near  Mica  Bay,  not  yet  brought  under  culti- 
vation. Stumps  of  the  quality  represented  by  the  sample  do  not 
occur  in  commercial  quantities  in  the  Coeur  d'Alene  Lake  region. 

SOUTH  IDAHO  REGION. 

The  wooded  country  throughout  the  South  Idaho  region  is  prac- 
tically undeveloped  and  without  railroads.  The  forests  remain  un- 
touched, except  in  a  few  places  where  small-scale  logging  operations 
have  been  carried  on  to  supply  local  mills.  The  timber  resources  are 
now  being  opened  up  for  extensive  logging  operations  to  supply  a 
mill  of  about  200,000  feet  daily  capacity  at  Barber,  some  6  miles 
out  from  Boise. 

Working  out  from  this  company's  logging  camp,  about  35  miles 
northeast  of  Boise,  a  hasty  survey  was  made  of  an  area  which  had 
been  cut  over  in  places  7  or  8  years  before  the  company  had  taken 
over  the  land  or  timber  rights.  Although  the  timber  throughout  this 
region  is  largely  yellow  pine,  few  of  the  stumps  appeared  pitchy 
enough  to  be  considered  "  rich."  Fully  50  per  cent  were  unsound 
and  therefore  worthless  for  distillation  purposes.  The  stand  of  yel- 
low-pine trees  or  stumps  24  inches  or  more  in  diameter  is  estimated 
as  not  exceeding  an  average  of  10  an  acre.  The  actual  count  for 
several  1-acre  plots,  taken  to  represent  a  close  stand,  was  20,  22,  and 
18  trees,  respectively.  Three  1-acre  plots  taken  to  represent  a  stand 
of  medium  density  ran  10,  6,  and  9  trees  an  acre.  Toward  the  other 
extreme  the  stand  diminished  to  where,  on  the  higher  ridges,  no  yel- 
low pine  was  encountered. 

According  to  one  of  the  company's  cruisers,  the  whole  of  the  Boise- 
Payette  pine  belt  is  very  much  like  the  land  traversed,  and  an  esti- 
mate of  10  yellow-pine  trees,  over  24  inches  in  diameter,  an  acre  is 
liberal. 

Of  the  total  number  of  yellow-pine  stumps  on  a  given  area  in  the 
old  cuttings  perhaps  1  out  of  25,  or  not  to  exceed  5  per  cent,  may  be 
considered  as  belonging  to  the  "  rich  "  or  "  pitchy  "  class,  probably 
40  to  50  per  cent  are  of  "  medium  "  quality,  and  the  remainder  of  a 
quality  from  which  it  was  not  considered  worth  while  to  take  a 
sample.  Four  samples  were  taken:  (a)  One  from  old  cuttings  to 
represent  the  "rich."  or  "pitchy,"  stumps;  (b)  one  of  "medium" 
quality,  from  the  old  cuttings;  (c)  one  from  green  stumps  from 
which  the  tree  had  been  felled  within  a  month  of  the  time  the  stumps 
were  shot ;  and  (d)  one  of  green  "  bull-pine  "  stumps.  Samples  c  and 
d,  included  because  they  were  the  stumps  and  logs  from  freshly 
fallen  trees,  though  containing  no  well-defined  heartwood,  had  an 
abundant  exudation  of  what  appeared  to  be  gum  on  the  freshly  cut 


20  BULLETIN  1003,   U.   S.   DEPARTMENT  OF  AGRICULTURE. 

surface.  There  was  a  little  dead,  down  wood,  and,  as  the  tops  of 
freshly  fallen  trees  did  not  appear  to  be  essentially  different  from 
those  seen  elsewhere  and  were  obtainable  nearer  Moscow,  a  sample 
of  this  wood  was  not  taken.  It  was  difficult  to  judge  the  relative 
quality  of  the  green  stumps  other  than  by  the  proportion  of  heart- 
wood  to  sapwood,  the  apparent  resin  content  of  the  heartwood  being 
quite  uniform.  The  proportion  of  truly  resinous  heartwood  to  sap- 
wood  varies  greatly,  however,  a  matter  of  importance  in  considering 
the  value  of  the  stumps,  owing  to  the  dearth  of  resin  in  the  sapwood. 
Probably  50  per  cent  of  the  green  yellow-pine  stumps  are  of  the 
quality  represented  by  sample,  and  the  remainder  of  inferior  quality, 
in  so  far  as  the  proportion  of  heartwood  to  sapwood  is  concerned. 

It  would  be  very  difficult  to  remove  these  stumps  unless  they  were 
taken  out  with  the  logging  operations,  because  of  the  fact  that  the 
mountainous  topography  and  limited  rainfall  preclude  an  extensive 
agricultural  development  in  the  wake  of  the  logging  operations.  The 
surface  of  the  land  presents  an  irregular  series  of  steep  ridges  be- 
tween which  wind  deep,  narrow  valleys,  where  spur  tracks  are  laid 
for  the  logs  which  are  skidded  down  the  hillsides  to  be  loaded  on 
tracks,  moved  as  fast  as  the  logs  are  taken  away.  The  stumps, 
therefore,  become  inaccessible  as  soon  as  the  tracks  are  taken  up. 

CRAIG   MOUNTAIN   REGION. 

The  yellow  pine  of  the  Craig  Mountain  region  is  a  practically 
pure  stand  over  an  area  some  10  miles  long  by  5  miles  wide  on  an 
elevated,  fairly  level  plateau.  Receding  from  this  central  area  the 
timber  opens  abruptly  on  Mission  Canyon  and  the  prairie  country 
toward  the  north  and  west,  and  less  abruptly  toward  the  east, 
while  toward  the  south  it  soon  becomes  mixed  with  fir  and  tamarack 
in  the  Salmon  River  country.  A  lumber  mill  with  a  daily  capacity 
of  about  125,000  feet  operates  in  Winchester,  which  is  centrally  lo- 
cated in  this  yellow-pine  belt.  Comparatively  little  of  the  timber 
had  been  cut. 

In  the  central  pine  area  the  stand  of  yellow  pine  varied  from 
400,000  to  800,000  board  feet  a  "forty,"  with  an  average  of  approxi- 
mately 20  stumps  over  30  inches  in  diameter  an  acre  where  the 
stand  was  closest.  The  mill  men  and  cruisers  consulted  agreed  that 
probably  25  per  cent  of  the  total  stand  throughout  this  region  is 
"bull  pine." 

Seven  samples  were  taken  from  this  region,  as  follows:  (a) 
Green  yellow-pine  stumpwood  from  several  stumps  blown  out  of 
the  roadbed  in  extending  spur  tracks  for  logging  purposes;  (b) 
medium  to  rich  stumpwood  from  stumps  blown  out  in  highway 
construction;  (c)  medium  to  poor  stumpwood  from  the  same  locality 
in  which  the  medium  to  rich  samples  were  obtained;  (d)  medium  to 


DISTILLATION   OF  STUMPWOOD.  21 

rich  stumpwood  shot  on  land  that  had  been  cut  over  4  or  5  years 
before;  (e)  dead,  down  yellow-pine  wood  collected  from  the  better 
quality  of  knots,  limbs,  and  trunks  of  trees  lying  throughout  the 
woods;  (/)  rich,  dead  tops  from  trees  felled  in  logging  operations, 
the  tops  of  which  were  dead  from  advanced  maturity,  and  dead 
standing  trees  that  had  died  from  the  same  cause;  (g)  the  better 
quality  of  tops  and  limbs  from  freshly  felled  trees.  In  addition, 
certain  other  samples  were  included  in  the  investigation.  The  sam- 
ple designated  "rich  stumpwood,  Viola"  was  from  western  yellow- 
pine  stumpwood,  from  a  ranch  located  near  Viola.  These  stumps, 
the  last  of  those  remaining  scattered  through  the  field,  had  been 
shot  out  with  dynamite,  and  the  best  snaked  to  the  house  for  fuel. 
It  was  from  this  lot,  the  weight  a  cord  of  which  was  estimated  to 
be  3,500  pounds,  that  a  sample  was  taken.  Trees  cut  from  these 
stumps  were  said  to  have  been  felled  35  or  more  years  before.  The 
wood  was  very  resinous,  and  to  all  appearances  the  same  as  the 
better  grades  of  pitch  pine  of  North  Carolina  or  other  southern 
States. 

The  sample  30-inch  stump  from  Priest  River,  obtained  from  a 
single  large  yellow-pine  stump  sent  in  from  Priest  River,  Idaho, 
was  selected  as  representing  the  best  of  the  rich,  or  pitchy,  stumps 
in  that  region.  It  had  been  blown  out  with  dynamite,  and  the  whole 
stump,  roots  and  body,  split  into  several  pieces  by  the  blast,  was 
weighed,  split,  and  reduced  to  stove-wood  size.  It  was  then  mixed 
by  being  thrown  together  in  a  heap  and  repiled  five  or  six  times, 
after  which  it  was  neatly  stacked  under  a  shed.  Dimensions  of 
the  pile  of  wood  thus  stacked  were  8x7x1.5  feet,  equal  to  a  volume 
of  84  cubic  feet.  The  stump  weighed  2,190  pounds,  so  that  as  piled 

o  1 9Q  v"  1 28 
this  wood  weighed -~r >  or  3,330  pounds  a  cord,  in  round 

numbers.  The  tree  cut  from  this  stump  had  been  felled  about 
seven  years,  not  long  enough  for  the  sapwood  to  have  rotted  away 
or  become  detached  from  the  lightwood  within.  This  sapwood  con- 
tained absolutely  no  turpentine  and  impoverished  the  wood  to  that 
extent.  It  is  estimated  to  have  constituted  20  per  cent  of  the  total 
volume  of  wood  in  the  stump. 

The  samples  identified  in  Table  14  as  "dead,  down  limbs"  and 
"fire-scarred  butts,  Viola"  were  from  yellow  pine  taken  near 
Viola.  Both  samples  were  very  resinous  for  these  classes  of  wood. 
There  was  not  a  sufficient  quantity  of  either  to  determine  closely  the 
weight  of  a  measured  cord.  Nevertheless,  if  these  facts  are  borne 
in  mind  and  these  samples  are  considered  with  other  samples  of  the 
same  classes  of  wood,  they  furnish  an  indication  of  the  products  to 
be  recovered  from  these  materials,  which  are  quite  plentiful  in  some 
sections.  In  some  regions  as  much  as  20  per  cent  of  the  butt  logs 


22  BULLETIN  1003,  U.   S.   DEPARTMENT   OF   AGRICULTURE. 

are  fire  scarred.    The  values  on  these  samples  given  in  Table  14  are, 
therefore,  only  estimates. 

SUMMARY. 

Northern  Idaho: 

Rich  stninpwood,  Priest  River. 
PotlatHi  I>e:iry  Region: 

Rich  stumpwood,  Viola. 

I  -.  a<l.  down  limbs,  Viola. 

Fire-srimvd  butt,  Viola. 

I'oor  stumpwnoil,  Deary. 

Rich  stumpwood,  Deary. 

Medium  stumpwood,  Deary. 

Dead,  down  limbs,  Deary. 

Rich  stumpwood,  Potlatch  (three  large  stumps). 

Medium  to  rich  stumpwood,  Potlatch  (from  stumps  other  than  the  three 

large,  rich  stumps). 
Coeur  d'Alene  Region: 

Rich  stumpwood,  Coeur  d'Alene  Lake. 

Medium  stumpwood,  Hayden  Lake. 
Somh  Idaho,  Boise  Region: 

Bull-pine  stumpwood,  Boise. 

Medium  stumpwood,  Boise. 

Rich  stumpwood,  Boise. 

Green  selected  stumpwood,  Boise. 
Craig  Mountain  Region: 

Selected  green  stumpwood,  Craig  Mountain. 

Rich  roadside  stumpwood,  Craig  Mountain. 

Medium  stumpwood,  Craig  Mountain. 

Rich,  cut-over  stumpwood,  Craig  Mountain. 

Dead,  down  limbs,  etc.,  Craig  Mountain. 

Dead  tops,  limbs,  etc.,  Craig  Mountain. 

Green  tops,  limbs,  etc.,  Craig  Mountain. 
Moscow : 

Tamarack  stumpwood. 

DISTILLATION  OF  SAMPLES. 

PREPARATION. 

The  wood  as  delivered  was  sawed  in  lengths  that  would  fit  into 
a  pile  of  cord  dimensions  and  split  into  pieces  approximately  2 
to  4  inches  in  diameter.  It  was  then  thrown  into  a  heap,  replied 
a  sufficient  number  of  times  to  render  it  uniform  in  quality,  corded, 
taking  care  to  pack  closely,  and  left  standing,  protected  from  the 
weather,  until  run.  The  entire  sample  thus  prepared  was  weighed 
on  a  portable  platform  scale  immediately  before  the  distillation, 
and  the  weight  calculated  from  its  measured  dimensions.  In  mak- 
ing these  weighings  3  separate  portions,  usually  of  175  pounds  each, 
were  taken  from  throughout  the  entire  pile  in  such  manner  as  to 
make  sure  that  each  sample  was  truly  representative  of  the  original 
field  sample. 

When  a  cord  of  wood  is  split  into  smaller  pieces  and  again  corded 
its  volume  is  increased  because  of  the  greater  proportion  of  voids 


DISTILLATION   OF   STUMPWOOD.  23 

or  air  spaces,  the  weight  decreasing  as  the  cubical  content  increases. 
An  increase  of  about  10  per  cent  is  said  to  result  from  reducing 
average  cordwood  to  the  size  in  which  the  wood  making  up  the 
samples  used  in  this  work  was  piled  and  measured,  from  which 
it  would  appear  that  the  weights  per  cord  on  which  the  yields  are 
computed  should  be  increased  by  10  per  cent.  Owing,  however,  to 
the  irregular  shape  of  the  pieces  of  stump  cordwood  and  the  care 
observed  in  piling  the  reduced  wood  closely,  it  is  believed  that  the 
observed  weights  are  not  essentially  lower  than  the  average  weight 
of  a  commercial  cord  of  western  yellow-pine  stumpwood  of  corre- 
sponding quality.  In  support  of  this  it  was  found  that  of  the  3 
cords  of  stumpwood  from  near  Deary,  Idaho,  piled  and  measured 
in  the  field,  when  corded  again  after  having  been  reduced  to  the 
size  in  which  they  were  used  in  the  retort,  one  measured  an  even 
cord,  one  19  per  cent  less  than  a  cord,  and  the  third  10  per  cent 
more  than  a  cord.  It  seems  unnecessary,  therefore,  to  use  other 
than  the  observed  weights  in  calculating  results. 

The  retort  distillations  were  made  on  charges  of  known  weights, 
varying  from  150  to  200  pounds,  depending  on  the  nature  of  the 
wood.  The  distillation  products  were  measured  in  liters  per  charge 
and  the  yields  reported  in  gallons  per  cord.  This  basis  of  state- 
ment was  selected  in  preference  to  the  more  exact  unit-of-weight 
basis,  the  ton,  for  example,  because  of  the  difficulty  of  estimating 
the  quantity  of  the  several  classes  of  wood  on  a  given  acre  and 
applying  the  results  to  the  problems  in  hand  on  other  than  the 
cord  basis.  The  yields  can  be  quickly  figured  to  the  ton  basis  from 
the  data  given  in  Table  14. 

APPARATUS. 

In  principle,  the  apparatus  (figs.  3  and  4)  is  essentially  an  oil- 
jacketed  retort  (a)  in  which  high-flash  cylinder  oil,  heated  to  the 
desired  temperature,  is  circulated  through  closely  spaced  heating 
coils  (&,  <?,  and  d)  within  the  retort.  The  coil  system  of  jacketing 
is  preferable  to  a  double  shell  in  that  it  insures  a  positive  flow  of 
the  heated  oil,  and,  by  dividing  the  coils  into  sections,  prevents  an 
excessive  drop  in  temperature  between  the  incoming  and  outgoing 
oil.  A  3-inch  layer  of  asbestos  lagging  and  pipe  covering  of  the 
same  material  protects  the  retort  and  exterior  piping  against  ex- 
cessive radiation.  A  coarse  wire-gauze  screen  placed  on  the  jacket 
coils  facilitates  removal  of  the  charcoal. 

The  motor-driven  oil  pump  (/)  takes  oil  from  the  overflow  tank 
(g)  and  discharges  it  through  the  gas-fired  oil  heater  (e)  into  the 
jacket  coils  (b  and  c),  from  the  other  end  of  which  it  flows  back 
into  the  tank  (g).  This  circulation  is  maintained  with  the  jacket  oil 
as  it  comes  from  the  heater  and  is  held  at  260°  C.  as  registered  on 


24  BULLETIN   1003,   U.   S.   DEPARTMENT  OF  AGRICULTURE. 

thermometer  1  until  the  turpentine  has  been  recovered.  The  tem- 
perature is  then  raised  to  343°  C.,  and  the  bottom  coil  (d)  made  to 
join  in  the  circulation  of  the  oil  by  opening  valve  o  until  destructive 
distillation  of  the  charge  has  been  effected.  Valves  m,  n,  and  o  are 
adjusted  (ordinarily  unnecessary)  so  that  thermometers  2,  3,  and  4, 
registering  the  temperature  of  the  return  oil  from  coils  &,  tf,  and  e?, 
respectively,  read  essentially  alike,  indicating  thereby  that  the  oil 
flows  equally  through  the  three  coils. 

PROCEDURE. 

Turpentine  is  present  in  resinous  wood,  along  with  rosin,  as  an 
oleoresin.  Subjected  to  the  designated  retort  temperature  this  oleo- 
resin  is  partially  sweated  out  and  escapes  from  the  pores  of  the  wood, 
losing  the  turpentine  by  vaporization,  while  the  resin  accumulates 


FIG.  3. — Plan  of  retort  used  for  distillation  of  samples. 

with  certain  decomposition  products,  as  pitch,  in  the  bottom  of  the 
retort.  The  distillation  is  therefore  conducted  in  two  stages. 

During  the  first  stage  the  turpentine  is  recovered,  and  the  result- 
ing rosin  liberated  from  the  wood  is  collected  in  the  bottom  of  the 
retort.  The  oil-bath  temperatures  during  this  stage  are  between  ap- 
proximately 220°  and  265°  C.  The  valve  to  the  bottom  coil  (d)  that 
lies  embedded  in  the  molten  rosin  is  then  opened,  and  the  tempera- 
ture of  the  circulating  oil  raised  to  343°  C.  This  brings  about  de- 
structive distillation  of  the  wood  and  the  rosin,  with  the  production 
of  pyroligneous  acid  and  the  formation  of  rosin  oils  containing  also 
creosote  and  other  constituents  derived  from  the  wood,  which  distil 
from  the  retort  in  two  stages  as  light  oil  and  heavy  oil. 

The  light  and  heavy  oils  come  over  with  the  aqueous  distillate 
(pyroligneous  acid)  resulting  from  the  clicniK-al  transformation  of 
the  wood  and  rosin  during  the  destructive  stage  of  the  distillation, 


DISTILLATION   OF   STUMPWOOD. 


25 


the  light  oil  between  260°  and  330°  C.,  and  the  heavy  oil  above 
330°  C.  A  strong  evolution  of  wood  gas,  which  burns  with  a  bright 
luminous  flame,  takes  place  while  the  heavy  oil  comes  over.  Char- 
coal and  pitch  are  the  end  products  of  the  distillation.  The  pitch  is 
drawn  off  through  a  plug  cock  in  the  bottom  of  the  retort  at  the  end 
of  a  run.  There  is  no  sharp  line  of  demarcation  between  the  stages 
in  which  the  distillation  is  conducted,  because  decomposition  of  the 
wood  takes  place  long  before  all  the  turpentine  has  distilled  over, 
and  to  effect  a  maximum  recovery  of  it  this  stage  of  the  distillation 


FIG.  4. — Elevation  of  retort. 


a,  Retort  shell. 

&  and  c,  Main  heating  coils. 

d,  Bottom  heating  coil. 

v,  Oil  heater. 

f,  Oil  circulating  pump. 

a,  Overflow  tank. 


h,  Worm  condenser. 

;',  Trapped  vent  pipe. 

k,  Oil  tank. 

I,  Overflow  catch. 

m,  n,  o,  Valves. 

1,  2,  3,  4,  Thermometers. 


must  be  continued  to  the  point  at  which  the  wood  is  converted  into 
a  brown  friable  substance  approaching  charcoal  in  its  nature.  This 
decomposition  sets  in  when  most  of  the  hygroscopically  held  moisture 
has  been  expelled  from  the  wood  (about  260°  C.),  and  is  made  appar- 
ent by  the  sharp  odor  of  the  distillate  and  development  of  a  reddish 
color  in  the  hitherto  colorless  aqueous  layer.  This  incipient  decom- 
position is  soon  attended  by  a  perceptibly  acid  taste  of  the  distillate, 
turbidity  of  the  turpentine  layer,  and  the  escape  of  noncondensable 
gases  (mostly  carbon  dioxid)  from  the  vent  pipe  (j).  This  point  in 


26  BULLETIN  1003,   U.   S.   DEPARTMENT   OF   AGRICULTURE. 

the  distillation  can  be  distinguished  by  an  experienced  person  within 
fairly  close  limits  by  means  of  the  changes  indicated. 

Contamination  with  decomposition  products  and  the  proportion  of 
heavier  oils,  that  subsequently  must  be  removed,  increase  rapidly  be- 
yond this  point.  This  comparatively  pure  fraction,  therefore,  is  not 
allowed  to  mingle  with  that  coming  over  beyond  this  point,  but  is 
collected  separately  as  "first  crude  turpentine,"  while  the  remainder 
constitutes  u  second  crude  turpentine."  The  aqueous  distillate  com- 
ing over  with  the  first  crude  turpentine,  being  practically  free  from 
alcohol  and  acid,  is  discarded,  but  that  from  the  second  turpentine  is 
collected  and  saved  with  the  pyroligneous  acid  obtained  throughout 
the  remainder  of  the  run.  The  temperature  being  held  fairly  con- 
stant, the  second  turpentine  fraction  is  continued  to  the  point  where 
the  flow  of  distillate  from  the  condenser  drops  below  a  practical 
limit,  equivalent  to  about  a  gallon  a  half  hour  in  these  experiments, 
and  the  oil  passing  over  no  longer  contains  turpentine,  as  shown 
when  it  is  dry  distilled. 

Along  with  the  drop  in  speed  of  condenser  discharge,  the  distillate 
suddenly  takes  on  a  true  consistency  and  undergoes  such  a  char- 
acteristic change  of  odor  that  there  is  no  mistaking  the  point  at 
which  all  turpentine  has  passed  over.  By  the  time  combustible 
gases  that  burn  with  a  pale  blue  flame  begin  to  escape  from  the 
vent  pipe.  The  bottom  coil  is  then  opened  and  the  temperature 
of  the  jacket  oil  run  up  to  approximately  345°  C.,  where  it  is  main- 
tained until  the  end  of  the  distillation.  The  oil  becomes  heavier  as 
the  temperature  rises,  until  presently  it  separates  from  the  aqueous 
portion  of  the  distillate  only  after  standing  for  some  time.  This 
marks  the  end  of  the  "  light-oil "  period.  The  greater  viscosity  of 
the  heavy  oil  and  its  characteristic  odor  are  further  relied  on  in 
cutting  the  light  and  heavy  oil  fractions.  The  discharge  of  non- 
condensable  gases  now  reaches  a  maximum,  and  these  suddenly  burn 
with  a  bright  luminous  flame  in  place  of  the  one  hitherto  blue. 

RESULT  OF   DISTILLATION. 

The  products  obtained  by  this  method  of  destructive  distillation 
;iiv.  therefore,  seven  in  number:  Crude  first  turpentine,  crude  second 
turpentine,  light  oil,  heavy  oil,  pyroligneous  acid,  pitch,  and  char- 
coal. The  temperatures  and  the  volumes  of  oil  and  acid  distillate. 
collected  were  entered  every  half  hour  in  a  log  kept  of  each  charge 
(Table  13).  The  distillates  were  collected  in  large  graduated  cylin- 
«i»-rs  and  the  oil  removed  from  the  aqueous  layer  in  separatory  fun- 
nels. The  sum  of  the  half-hour  oil  readings  tends  to  be  a  little  high 
because  of  the  imperfect  separation  of  the  water  and  the  volume 
of  the  oil  accumulated  by  the  end  of  the  period  a  little  low  because 


DISTILLATION   OF   STUMPWOOD. 


27 


of  unavoidable  transfer  losses.     The  mean  of  the  two,  therefore, 
is  used  in  calculating  gallons  a  cord. 

TABLE  13. — Specimen  log  of  a  run  of  150  pounds  of  Boise  medium  yellows-pine 

stumptvood. 


Time. 

Temper- 
ature of 
oil  bath. 

Products  obtained. 

Com- 
bined oil 
and  wa- 
ter. 

Remarks. 

Oil. 

Water. 

A.  M. 

8.25 
10.00 
10.30 
11.00 
11.30 
12.00 
12.30 

P.M. 

1.00 
1.30 
2.00 
2.30 
3.00 
3.30 
4.00 

4.30 
5.00 
5.30 
6.00 
6.10 
6.30 
7.00 
7.30 
8.00 
8.30 
9.00 
9.30 
10.00 

°C. 

Cc. 

Cc. 

Cc. 

Lighted  gas,  started  pump,  closed  bottom  coil. 
Distillate  started. 

Took  sample  acid  liquor  for  analysis. 
Noncondensable  white  vapors  first  appeared;  last 
of  first  turpentine. 

First  of  second  turpentine;  began  saving  acid  liquor. 
Gas  from  vent-pipe  burns. 

Last  of  second  turpentine;  ran  up  temperature; 
opened  bottom  coil. 
First  of  light  oil. 

Last  light  oil. 
Heavy  oil  started. 

Shut  down,  drew  pitch;  drip  150  cc.  heavy  oil  by 
next  morning. 

223 
238 
250 
260 
261 
256 

261 
261 
261 
260 
260 
263 
258 

281 
298 
310 
319 
322 
327 
336 
340 
344 
346 
342 
342 
342 

410 
540 
500 
495 
430 

360 
385 
370 
300 
235 
180 
160 

135 
165 
170 
380 
230 

790 
1,100 
940 
800 
640 

485 
530 
570 
590 
590 
570 
560 

490 
560 
830 
1,550 
740 

3,050 
4,050 
2,050 
1,550 
1,100 
600 
240 
90 

CHARACTER   OF   CHANGES    OCCURRING    DURING   DISTILLATION. 

Wood  tissue  is  made  up  primarily  of  cellulose,  which,  built  up 
into  cells  and  tissue,  constitutes  the  structural  element  of  plants, 
and  lignin,  which  occurs  as  an  incrusting  matter  or  coating  on  the 
cell  walls.  In  resinous  wood  there  is  a  further  deposit  in  the  wood 
tissue  of  oleoresin  from  which  the  turpentine  and  pine  oils  are  ob- 
tained when  the  wood  is  subjected  to  distillation  at  a  relatively  low 
temperature. 

As  previously  explained,  the  nonvolatile  substance  remaining 
when  the  volatile  oils  are  distilled  from  the  oleoresin  is  rosin,  a  sub- 
stance largely  composed  of  abietic  acid.  Toward  the  end  of  the  tur- 
pentine stage  of  the  distillation  the  contents  of  the  retort  may  be 
considered  as  made  up  principally  of  abietic  acid,  cellulose,  and 
ligninlike  substances,  all  of  which  are  composed  of  the  elements 
carbon,  oxygen,  and  hydrogen.  The  molecules  of  these  substances, 
being  comparatively  large  and  complex,  are  readily  broken  down 
by  the  application  of  heat  into  a  series  of  simpler  compounds,  some 
of  which,  reacting  the  one  on  the  other,  may  form  still  other  com- 


28  BULLETIN   1003,   U.   S.   DEPARTMENT  OF   AGRICULTURE. 

pounds.  Of  them  all,  water  is  the  compound  formed  in  the  greatest 
quantity,  because  of  the  fact  that  oxygen  and  hydrogen  constitute 
55  per  cent  of  cellulose,  the  principal  wood  constituent.  This  water, 
holding  in  solution  numerous  other  compounds,  produced  simtdtane- 
ously  with  its  formation,  is  referred  to  in  this  bulletin  as  the  "  acid 
liquor,"  an  exceedingly  complex  liquid  of  a  wine-red  color,  having 
a  sharp,  tarry  odor  and  strong  acid  reaction.  In  addition  to  water. 
it  is  largely  made  up  of  acetic  acid,  methyl  or  wood  alcohol,  tar  acids, 
oils,  esters  and  acetone  aldehyde  bodies,  together  with  small  propor- 
tions of  numerous  other  compounds  of  an  unknown  nature. 

It  is  not  meant  to  convey  the  idea  that  these  changes  occur  in 
clear-cut  stages.  Neither  is  it  strictly  true  that  the  charge  in  the 
retort  is  in  reality  made  up  of  cellulose,  lignin,  and  abietic  acid  or 
rosin  at  any  time  during  the  distillation,  for  these  compounds,  owing 
to  their  instability  toward  heat  when  dry,  undergo  progressive 
changes  as  the  moisture  is  more  and  more  completely  driven  out 
of  the  wood,  before  the  recovery  of  turpentine  is  complete.  Though 
the  period  during  which  the  distillation  products  do  not  result  from 
decomposition  of  the  wood  substances  and  the  destructive  stages  of 
the  distillation  merge  into  each  other  or  overlap,  the  nature  of  the 
changes  taking  place  is  essentially  as  set  forth. 

DISTILLATION  OF  WOOD  (EXOTHERMAL)  AND  OF  ROSIN  (ENDOTHERMAL). 

The  chemical  reactions  brought  about  during  the  destructive  dis- 
tillation of  cellulose  are  exothermal,  that  is,  heat  is  given  off  during 
the  changes  taking  place  once  the  action,  for  which  a  temperature  of 
270°  C.  is  necessary,  has  been  started.  The  amount  of  heat  thus  lib- 
erated was  found  by  Klason,  Heidenstam,  and  Norlin  5  to  be  equiva- 
lent to  4.6  per  cent  of  the  calorific  or  fuel  value  of  the  wood  (pine). 
The  reactions  involved  in  the  decomposition  of  rosin  by  destructive 
distillation,  in  the  course  of  which  rosin  oils  are  formed,  however, 
cease  unless  an  adequate  supply  of  heat  is  maintained  throughout  the 
distillation.  This  is  due  to  the  fact  that  the  changes  taking  place, 
instead  of  liberating,  take  up  heat,  being  "  endothermic  "  reactions. 

These  facts  are  of  significance  in  view  of  the  difference  in  behavior 
observed  when  the  more  highly  resinous  wood  and  that  containing 
but  little  resinous  matter,  such  as  "  bull  pines,"  are  distilled.  In  the 
case  of  the  more  highly  resinous  wood  a  decided  exothermic  effect 
was  observed  while  the  destructive  stage  of  the  distillation  was  in 
progress,  continuance  of  the  high  temperature  (343°  C.)  being  neces- 
sary to  carry  the  distillation  to  completion.  In  the  distillation  of 
"bull  pine"  in  the  same  state  of  dryness,  however,  the  reaction  be- 


.  Kemi.  Min.  C.-ol.,  Hand  :',.  N.I.   in,  H,.ft  1>.     Published  l»y  th»-  Royal  Academy  of 
Science*  at  Stockholm. 


DISTILLATION   OF   STUMPWOOD.  29 

came  so  violent  when  a  temperature  of  about  300°  C.  was  reached  that 
the  distillation  could  practically  be  completed  without  further  heat- 
ing, and  in  less  time  than  the  richer  wood  with  continued  heating. 

It  was  necessary,  therefore,  in  distilling  the  "  bull  pine  "  to  watch 
the  oil-bath  thermometer  carefully  in  running  up  the  temperature 
for  destructive  distillation  and  turn  off  the  heater  flame  when  this 
period  was  reached.  The  reaction  progresses  so  rapidly  that  the  dis- 
charge of  gas  and  vapors  may  exceed  the  otherwise  ample  condenser 
capacity,  and  loss  of  distillate  result  from  imperfect  condensation. 
The  difference  in  behavior  is  due  to  the  fact  that  the  richer  wood  con- 
tains a  much  greater  ratio  of  rosin  to " cellulose.  The  heat  set  free 
during  decomposition  of  the  wood  substance  is  more  than  offset  by 
that  required  to  effect  decomposition  of  the  rosin  in  such  wood,  and 
additional  heat  must  be  supplied  to  insure  the  decomposition  of  rosin 
and  the  distillation  of  the  products. 

The  fact  that  in  the  destructive  distillation  of  nonresinous  woods 
enough  heat  above  a  certain  temperature  is  developed  to  complete  the 
distillation  without  the  application  of  heat  from  outside  sources, 
necessitates  the  installation  of  larger  condensers  in  the  distillation 
of  nonresinous  woods  than  are  needed  in  the  distillation  of  resinous 
woods.  When  the  exothermal  reaction  begins,  it  proceeds  so  rapidly 
that  the  condensers,  which  in  the  earlier  stages  were  large  enough  to 
condense  all  condensable  material,  can  no  longer  do  so,  and  a  loss  of 
valuable  products  occurs  if  the  condensers  are  too  small  to  meet  all 
the  requirements  that  may  be  placed  upon  them  during  the  exother- 
mal period. 

YIELDS. 

The  yields  of  crude  products  obtained  in  the  retort  distillation,  and 
of  the  refined  turpentine  and  pine  oil  for  each  sample,  are  given  in 
Table  14.  A  summary  of  these  tabulations,  giving  the  average  re- 
covery from  the  various  grades  of  wood  distilled,  is  given  in  Table  19. 


30 


BULLETIN   1003,   U.   S.   DEPARTMENT  OF   AGRICULTURE. 


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DISTILLATION    OF   STUMPWOOD.  31 

CRUDE  PRODUCTS  OF  RETORT  DISTILLATION. 

CRUDE   WOOD   TURPENTINE. 

The  crude  wood  turpentine  is  distilled  from  the  wood  during  the 
first  stage  of  the  destructive  distillation.  During  this  first  stage  of 
distillation  the  turpentine  passes  over  for  the  most  part  unchanged, 
as  it  probably  exists  in  the  wood  tissue.  The  crude  first  turpentine, 
therefore,  is  nearly  free  from  pyroligneous  bodies.  It  is  often  light 
in  color,  and  usually  possesses  an  agreeable  odor.  It  has  a  specific 
gravity  of  about  0.875  at  20°  C.,  a  refractive  index  of  about  1.4768 
at  the  same  temperature,  and  an  initial  boiling  point  of  about  164°  C. 

The  crude  second  turpentine  necessarily  contains  more  of  the  pyro- 
ligneous or  heat-decomposition  products  and  of  the  heavier  pine  oils, 
since  the  retort  operator  cuts  the  distillate  at  the  first  signs  of  de- 
composition of  the  wood,  indicated  by  the  appearance  of  noncon- 
densable  gases,  and  collects  the  remainder  of  the  turpentine  as  "  sec- 
onds." The  heat-decomposition  products  of  the  rosin  and  wood 
constituents  consist  of  acids,  alcohols,  ketones,  phenols,  aldehydes, 
etc.,  the  nature  and  quantity  of  which  depend  on  the  temperature 
and  rate  at  which  the  turpentine  stage  of  the  distillation  is  conducted. 
This  crude  second  turpentine  is  darker  than  the  crude  first,  and  its 
color  is  sharper  and  more  suggestive  of  wood  decomposition.  It  has 
a  specific  gravity  of  about  0.910  at  20°  C.,  a  refractive  index  of  about 
1.4850  at  the  same  temperature,  and  an  initial  boiling  point  of  about 
130°  C.  (due  to  the  presence  of  decomposition  products). 

The  difference  between  these  two  crude  turpentines  is  well  set  forth 
in  Table  15. 

TABLE  15. — Products  of  dry  distillation  of  crude  turpentine  at  760  mm.  pressure. 


Temperature  of  distillation  (°  C.). 

First 
turpen- 
tine. 

Second 
turpen- 
tine. 

Below  170    

Per  cent. 
9  3 

Per  cent. 
7  5 

Between  170  and  175.  . 

52  8 

9  06 

Between  175  and  180.  . 

16  0 

18  05 

Between  180  and  185.  . 

18  02 

Residue  

21  9 

47  37 

The  details  of  refining  the  crude  turpentine  are  discussed  on 
page  56. 

LIGHT   OIL. 

The  crude  light  oil  is  brownish  black,  has  a  sharp,  penetrating, 
empyreumatic  odor,  an  average  specific  gravity  of  about  0.995,  a 
refractive  index  of  1.514,  each  at  20°  C.,  and  an  acid  value  of  about 
29.  Its  average  viscosity  at  25°  C.  is  2.58°  Engler.  The  yield  is 
about  4^  gallons  a  cord  of  rich  wood.  Distilled  in  the  ordinary 
manner  at  atmospheric  pressure,  using  a  fractionating  column,  it 
has  an  uncertain  initial  boiling  point,  around  70°  C.,  due  to  the  pres- 


32  BULLETIN    KHia,    r.    s.    I'KI'AKTMKXT   OF   AGRICULTURE. 

ence  of  water  and  other  low-boiling  constituents,  which  rises  rapidly 
to  160°  C.  The  complex  nature  of  this  material  is  indicated  by  its 
wide  temperature  range  when  subjected  to  distillation.  Typical 
results  are  shown  in  Table  16. 

TAP.I.K    Hi.  -  -IH.xtilliitinn   data   of  ennifinsite  entile   lifilif   dl. 


Material  distilling  between— 

Amount. 

Material  distilling  between— 

Amount. 

55°  and  120°  C    . 

Per  cent. 
3.5 

230°  and  350°  C.  .                    

Per  cent. 
54.3 

120°  and  180°  C 

13  6 

Watery  layer 

1.8 

1  80°  and  230°  C... 

21.1 

Residue  soft  pitch  

5.7 

On  subjecting  the  various  samples  of  crude  light  oil  to  dry  dis- 
tillation at  atmospheric  pressure,  using  a  fractionating  column,  an 
average  of  34.5  per  cent  was  found  to  distil  below  225°  C.  Of  the 
total  distillate  an  average  of  1.8  per  cent  was  aqueous.  This  aque- 
ous portion,  as  well  as  the  lighter  portions  of  the  oily  distillate,  con- 
tains quantities  of  acetic  acid,  methyl  alcohol,  and  acetone.  The 
difficulty  of  their  recovery  in  a  state  pure  enough  for  quantitative 
estimation  is  such,  however,  that  it  is  as  yet  possible  only  to  esti- 
mate the  quantities  of  these  bodies  present. 

On  treating  the  distillate  obtained  below  225°  C.  with  an  excess 
of  20  per  cent  alkali  solution,  a  marked  contraction  in  volume  of  the 
oil  and  decided  heating  were  observed.  When  the  oil  thus  treated 
was  steam  distilled  to  exhaustion,  87  per  cent  (1.3  gallons  a  cord) 
of  total  distillate  was  recovered  as  a  rather  sharp-smelling,  light- 
yellow  oil  having  an  uncertain  initial  boiling  point  of  about  125°  C. 
On  dry  distilling  this  steam-distilled  oil,  60  per  cent  passed  over 
below  175°  C.,  and  the  remainder  distilled  up  to  250°  C.  In  its 
behavior  on  distillation  it  shows  a  close  resemblance  to  rosin  spirits. 

By  treating  the  crude  light  oil  with  alkali  and  distilling  with 
steam  as  in  the  refining  of  the  crude  turpentine,  10  per  cent  (0.4 
gallon  a  cord)  of  the  oil  is  recovered  as  refined  rosin  spirits  dis- 
tilling at  from  130°  to  200°  C.  and  20  per  cent  as  a  pine-oil  fraction 
distilling  at  from  175°  to  275°  C.  The  pine-oil  fraction  distilling 
at  from  175°  to  275°  C.  has  a  lemon-yellow  color  like  refined  pine 
oil,  but  an  unpleasant,  altogether  different  odor,  and  can  not  be  con- 
sidered as  pine  oil,  except  perhaps  in  certain  of  its  constituents. 
Fifty  per  cent  of  it  distils  below  200°  C. 

The  residue  from  this  steam  distillation  of  the  crude  light  oil 
forms  a  heavy  emulsion  with  the  alkali  present.  On  the  addition  of 
acid  about  10  per  cent  of  the  original  oil  separates  out  as  a  heavy  tar 
that  settles  to  the  bottom.  The  remaining  oil  has  about  the  density  of 
water,  slowly  floating  to  the  top,  is  dark,  and  has  a  mild  odor. 

Distilled  in  a  vannim  of  from  10  to  20  mm.,  80  to  85  per  cent 
(3.2  to  3.4  gallons  a  cord)  of  the  crude  light  oil  is  recovered  as  a 


DISTILLATION   OF   STUMP  WOOD.  33 

clear,  brownish-red  oil  that  darkens  on  standing  and  has  a  creosote 
odor.  The  residuum  from  this  distillation  is  a  hard  pitch.  Ke- 
peated  rectification  of  this  light  oil  has  given  a  series  of  fractions 
ranging  from  166°  to  176°.  The  fraction  from  174°  to  176°  gives 
an  oily  bromin  addition  product.  Apparently  it  adds  hydrochloric 
acid  gas  to  form  needlelike  crystals  after  standing  a  number  of  days, 
but  all  attempts  to  make  a  nitrosyl  chlorid  were  fruitless. 

The  yield  of  crude  light  oil,  compared  to  that  of  heavy  oil,  is 
small.  Since  the  light  oil  differs  but  little  from  the  heavy  oil, 
it  probably  will  be  found  expedient  to  collect  and  market  or  work 
it  up  along  with  the  heavy  oil  in  the  operation  of  a  commercial 
plant.  One  application  to  which  this  crude  oil  may  be  put  is  as  a 
vehicle  for  cheap  paints  and  shingle  stains,  and  other  such  pur- 
poses for  which  certain  of  the  creosote  oils  are  now  used. 

HEAVY  OIL. 

The  properties  of  the  heavy  oil  which  results  chiefly  from  the 
destructive  distillation  of  rosin  resemble  strongly  those  of  rosin  oil. 
The  crude  oil  also  contains  decomposition  products  of  the  wood  tis- 
sue, to  which  extent  it  is  like  wood  creosote  and  rosin  oil.  The 
crude  heavy  oil  is  slightly  heavier  than  water  (average  density 
of  1.048  at  20°  C.),  is  brownish  black,  and  has  a  penetrating,  creosote- 
like  odor.  The  average  viscosity  at  25°  C.  is  11.9°  Engler.  Like 
the  light  oil,  it  is  comparatively  unknown  and  untried,  and  there- 
fore lacks  a  well-established  market  value. 

Heavy  oil  is  one  of  the  important  products  obtained  in  the  dis- 
tillation of  resinous  woods.  The  yield  is  exceedingly  variable,  run- 
ning from  about  75  gallons  a  measured  cord  of  very  rich  stump- 
wood  to  as  little  as  16  gallons  from  dead,  down  wood.  Making  up 
a  large  proportion  of  the  total  volume  of  oil  recovered,  its  disposal 
to  the  best  advantage  possible  is  essential  to  the  profitable  operation 
of  a  commercial  plant  where  the  process  is  similar  to  that  employed 
in  this  investigation.  Consequently,  certain  experiments,  looking  to 
the  most  probable  means  by  which  an  enhancement  in  the  value  of 
the  crude  oil  may  be  expected,  were  conducted. 

From  the  results  of  laboratory  work  it  was  found  that  in  sepa- 
rating its  low-boiling  fraction  by  distilling  at  atmospheric  pressure 
from  a  flask  fitted  with  a  Hempel  column,  distillation  begins  at  an 
uncertain  initial  temperature  of  about  85°  or  90°  C.,  with  an  average 
recovery  of  25  per  cent  (8.7  gallons  a  cord)  below  225°  C.  This 
fraction  is  quite  similar  to  the  corresponding  fraction  obtained  from 
the  crude  light  oil. 

The  crude  heavy  oil  can  be  used  with  some  success  for  flotation 
purposes.  In  other  fields  of  industry  it  must  be  sold  largely  in  com- 
petition with  products  commonly  obtained  from  coal  tars  such  as 
60953°— 21 3 


34  BULLETIN   1003,   U.   S.   DEPARTMENT  OF  AGEICULTURE. 

are  used  in  the  manufacture  of  roofing  cement  and  shingle  stains, 
and  as.  a  softener  and  binder  in  treating  heavy  cotton  cloths  with 
metallic  resinates,  for  water  and  mildew  proofing  purposes.  In  Rus- 
sia a  similar  pine  product  is  used  extensively  as  a  leather  dressing  for 
harnesses,  boots,  etc.  Either  by  itself  or  mixed  with  tar  it  might 
be  successfully  employed  in  the  preparation  of  cordage,  tar  soap, 
moth-proof  paper  bags,  leather  dressings,  etc.  Bacteriological  tests 
have  shown  it  to  possess  a  phenol  coefficient  equal  to  one-half  that 
of  carbolic  acid. 

Both  the  light  and  heavy  crude  oils,  as  well  as  some  of  the  other 
products  of  this  investigation,  were  examined  to  determine  their 
adaptability  to  flotation  purposes  by  the  United  States  Bureau  of 
Mines  at  Salt  Lake  City,  Utah  (page  54),  and  also  by  several  mining 
companies  operating  in  the  western  States.  One  company  reported 
that  while  all  the  pine  oils  were  generally  satisfactory  for  zinc  ores, 
the  crude  light  oil  and  a  partially  refined  pine  oil  were  particularly 
good.  Another  stated  that  the  results  differed  only  slightly  from 
those  obtained  with  oil  from  the  southeastern  pines,  this  being  one  of 
the  most  effective  oils  for  flotation  purposes.  Probably  all  would  be 
good  for  copper  ores  if  used  in  conjunction  with  kerosene  sludge  acid. 

PITCH. 

The  average  yields  of  pitch  from  all  classes  of  wood  are  not  widely 
different  except  those  from  dead,  down  wood,  which  are  much  smaller 
than  those  from  richer  woods.  No  tests,  either  physical  or  chemical, 
have  been  developed  with  which  to  compare  the  qualities  of  the 
different  samples  of  resinous-wood  pitch  found  in  commerce,  other 
than  the  presence  or  absence  of  foreign  matter,  and  no  specifications 
on  the  basis  of  which  to  make  such  comparisons  have  been  estab- 
lished. For  this  reason,  and  because  its  most  important  application 
is  for  impregnating  fibers  in  the  manufacture  of  oakum  and  cordage, 
and  for  closing  seams  in  the  decks  of  vessels,  when  it  is  combined  in 
various  proportions  with  tar  and  turpentine  to  secure  the  consistency 
desired,  a  systematic  examination  of  individual  samples  of  this  ma- 
terial has  not  been  made.  These  differ  so  little,  the  only  apparent 
distinction  that  could  be  drawn  between  samples  being  a  slight  varia- 
tion in  their  relative  hardness,  that  a  general  description  will  suffice. 

The  pitch  is  a  black,  brittle  to  slightly  pliant  solid,  having  a 
specific  gravity  of  1.144  to  1.148  and  in  hardness  varying  from  that 
of  common  rosin,  in  the  more  brittle,  to  that  holding  a  finger  print 
and  possessing  slight  tackiness  in  the  softer  samples  at  ordinary  tem- 
peratures. So  susceptible  is  it  to  temperature  changes  that  samples 
which  were  found  to  be  tough  or  pliant  through  the  day  Inviunc  quite 
brittle  during  the  night.  Its  melting  point  is  consequently  very  in- 
definite. It  behaves  like  a  viscous  fluid  at  75°  to  100°  C,,  is  sirupy 


DISTILLATION   OF   STUMPWOOD.  35 

at  100°  to  125°  C.,  and  free  flowing  at  about  125°  to  150°  C.  It  is 
practically  devoid  of  taste  or  odor,  and  dissolves  readily  in  turpen- 
tine, but  only  very  sparingly  in  either  cold  or  hot  alcohol,  differing  in 
this  respect  from  common  or  black  rosin.  Its  acid  value  was  found 
to  be  2,  extracted  with  alcohol,  against  150  to  180  for  black  rosin. 

It  differs  from  what  is  purchased  under  Government  contracts  for 
"  North  Carolina  pitch  "  in  being,  on  the  whole,  blacker,  and  some- 
what softer,  and  in  having,  therefore,  a  generally  lower  melting 
point.  It  is  believed,  however,  that  this  will  not  detract  from  its 
value  in  the  uses  previously  enumerated,  but  rather  that  its  somewhat 
greater  pliability  may  be  found  to  be  advantageous. 

CHARCOAL. 

The  charcoal  obtained  in  these  experiments  from  western  yellow 
pine,  especially  that  from  the  richer  or  more  resinous  samples  of 
wood,  is  very  soft  and  friable  It  retains  an  appreciable  amount  of 
bituminous  matter,  due  undoubtedly  to  incomplete  distillation,  which 
causes  it  to  burn  with  a  long,  smoky  flame.  Its  possible  application  is 
suggested  in  industries  where  powdered  fuel  is  used,  or  in  metallurgi- 
cal operations  in  which  the  crushing  strength  is  not  a  prime  requisite. 

The  charcoal  from  "  bull "  pine  was  in  every  respect  superior  to 
that  obtained  from  yellow  pine  proper,  and,  in  general,  the  quality 
of  the  charcoal  fell  off  as  the  rosin  content  of  the  wood  increased. 
Compared  to  that  from  hardwood,  the  western  yellow-pine  char- 
coal must  be  considered  of  inferior  quality,  especially  as  to  hardness. 

Tamarack  charcoal  has  a  much  denser  structure  and  is  not  so 
friable  as  that  obtained  from  yellow  pine.  Moreover,  it  is  clean  or 
free  from  bituminous  matter,  and  appears  to  be  quite  similar  to  hard- 
wood charcoal. 

ACID  LIQUOR    (PYROLIGNEOUS  ACID). 

The  specimen  log  of  a  run  (page  27)  shows  that  an  aqueous  dis- 
tillate which  is  nearly  pure  water  comes  over  with  the  turpentine  at 
the  beginning  of  a  distillation  and  is  rejected.  As  the  heating  is 
continued,  the  wood  tissue  begins  to  decompose  and  the  aqueous 
liquor  takes  on  a  straw  color.  From  this  point  it  contains  acids  and 
alcohol  in  varying  quantities,  and  constitutes  a  true  acid  liquor, 
which  in  these  experiments  was  retained  and  examined. 

The  acid  liquor  results  from  chemical  transformations  of  bodies 
making  up  the  wood  tissue  and  rosin  contained  in  the  wood,  brought 
about  by  heating  the  wood  to  a  sufficiently  high  temperature.  This 
reaction  is  a  true  chemical  process,  none  of  the  compounds  found 
in  the  liquor  occurring  in  the  untreated  wood.  The  action  is  alto- 
gether different,  therefore,  from  the  recovery  of  turpentine  and  pine 
oils,  the  separation  of  which  is  effected  by  a  physical  change  of 


36 


BULLETIN  1003,   U.   S.   DEPARTMENT  OF   AGRICULTURE. 


state.  In  other  words,  the  heat  serves  only  to  convert  these  oils 
into  vapors,  which,  after  being  cooled  in  the  condenser,  are  col- 
lected essentially  as  originally  present  in  the  wood. 

The  three  important  constituents  of  acid  liquor  are  acetic  acid, 
methyl  (wood)  alcohol,  and  acetone.  Up  to  the  present  time  these 
products  have  been  obtained  almost  exclusively  from  hardwood. 
Owing  to  the  greater  amount  of  tarry  substances  present,  softwood 
acid  liquor  is  extremely  difficult  to  free  from  this  constituent,  and 
the  calcium  acetate  made  therefrom  is  inferior  in  quality  to  that 
from  hardwood  acid  liquor.  The  yield,  consisting  of  methyl  alcohol 
and  acetone,  is  also  substantially  lower  than  that  from  hardwoods. 

The  proportions  of  acid,  alcohol,  and  acetone  as  found  in  these 
western  yellow-pine  acid  liquors  (Table  17)  were  obtained  by 
analyzing  a  composite  sample  of  acid  liquor  from  each  set  of 
charges  run  on  the  various  kinds  of  wood.6 

TABLE  17. — Composition  of  add  liquor*. 


Grade  and  source. 

Acid 
liquor, 
per 
cord. 

Acetic  acid. 

80  per 
cent 
acetate 
of 
lime 
(calc. 
from 
acetic 
acid), 
per 
cord. 

Methyl  alco- 
hol. 

Acetone. 

Dissolved  oils 

and  tars. 

Per 

liter. 

Per 

cord. 

Per 
liter. 

Per 
cord. 

Per 

liter. 

Per 

cord. 

Per 

liter. 

Per 
cord. 

Poor  stump  wood,  Deary  
Rich  stumpwood,  Deary  
Medium  stumpwood,  Deary.  . 
Dead,  down  wood,  Deary  
Rich     stumpwood,     Coeur 
d'Alene 

Galls. 
59.4 
55.9 
54.3 
53.4 

60.9 

61.4 
64.3 
63.9 
59.5 

63.6 
69.2 
62.4 
63.6 
74.0 
75.8 
63.2 
80.8 
66.6 
65.7 

Gms. 
67.76 
64.67 
67.82 
64.49 

64.37 

65.44 
77.55 
64.67 
68.12 

71.05 
70.40 
73.41 
65.12 
41.95 
48.35 
57.90 
49.67 
58.21 
59.72 

Lbs. 
33.6 
30.2 
30.7 
28.7 

32.7 

33.5 
41.6 
34.5 
33.8 

37.7 
40.7 
38.2 
34.6 
25.9 
30.6 
30.5 
33.5 
32.4 
32.7 

Lbs. 
55.3 

49.7 
50.5 
47.2 

53.8 

55.1 

68.5 
56.8 
55.6 

62.0 
67.0 
62.9 
56.9 
42.6 
50.4 
50.2 
55.1 
53.3 
53.8 

Galls. 
27.82 
25.45 
26.11 
25.98 

23.19 

27.35 
29.37 
25.21 
25.34 

27.64 
26.18 
30.17 
29.27 
13.88 
24.32 
27.71 
28.09 
28.21 
18.26 

Goto. 
2.10 
1.80 
1.79 
1.76 

1.79 

2.13 
2.40 
2.04 
1.91 

2.23 
2.29 
2.38 
2.36 
1.30 
2.34 
2.22 
2.S7 
2.38 
1.54 

Gms. 
2.24 
2.77 
2.44 
2.33 

2.00 

1.92 
2.21 
2.12 
2.16 

2.42 
2.26 
1.81 
2.07 
1.49 
1.75 
2.09 
1.73 
2.10 
1.69 

Galk. 
0.20 
.16 
.16 
.15 

.15 

.15 
.18 
.17 
.16 

.19 
.19 
.14 
.16 
.14 
.17 
.16 
.17 
.17 
.14 

Gms. 

Lbs. 

120.08 
L84.68 

156.86 

122.34 

136.  11 
172.  12 
133.90 
128.54 

161.  16 
159.29 
152.37 
143.31 
66.15 
11'.'.  71 
117.  M 

78,  '.'s 
114  « 
I  JO.  83 

56.0 
60.9 
69.9 

62.2 

69.7 
92.3 
71.4 
63.8 

85.5 
92.0 
79.3 
76.0 
40.8 
75.7 
62.1 
53.2 
63.6 
66.1 

Medium  stumpwood,  Hayden 
Lake 

Bull-pine  stumpwood,  Boise.. 
Medium  stumpwood,  Boise... 
Rich  stumpwood,  Boise  
Green  selected  stumpwood, 
Boise 

Green  selected  stumpwood, 
Craig  Mountain  

Rich  cut-over  stumpwood, 
Craig  Mountain  ... 

Rich  ^cut-over  stumpwood, 
roadside,  Craig  Mountain... 
Tamarack  stumpwood,  Mos- 
cow Mountain 

Selected  dead,  down  wood, 
Craig  Mountain  

Selected    dead    tops,   Craig 
Mountain  

Selected  green  tops  and  limbs, 
Craig  Mountain 

Medium  stumpwood,  road- 
side, Craig  Mountain  
Rich  stumpwood,  near  Pot- 
latch 

"Tin-   analyses  of   tin-   arid    liquors   w.-iv   made    by    V.    E.    (Jrotlis.  h    :iml    C.    <'.    Sponcer, 
I'.uivaii  <>f  riimiistry,   I'nit.d  States  Department  of 


DISTILLATION   OF   STUMPWOOD.  37 

The  yield  of  calcium  acetate  is  approximately  but  one-fourth  of 
that  generally  obtained  in  distilling  the  best  hardwoods.  Probably 
on  a  commercial  scale  the  yields  would  be  somewhat  less  than  those 
shown  by  the  analyses.  The  yield  of  wood  alcohol  also  is  but  one- 
fourth  of  that  generally  obtained  in  hardwood  distillation. 

PRODUCTS  OBTAINED  IN  REFINING  CRUDE  TURPENTINE. 

REFINED  TURPENTINE. 

In  order  to  separate  the  valuable  turpentine  constituents  of  the 
crude  turpentines  from  the  pyroligneous  and  resinous  heat-decompo- 
sition products  of  the  wood,  the  crude  turpentines  are  first  treated  with 
caustic  soda,  which  combines  with  acids  and  resinifies  the  aldehydes 
and  phenols,  forming  nonvolatile  compounds.  By  a  subsequent  steam 
distillation  the  turpentine  and  pine  oil  are  recovered.  Just  as  in  the 
case  of  the  original  retort  distillation  of  the  wood,  the  oily  products 
of  the  steam  distillation  are  separated  into  several  fractions.  The 
first  product  is  called  "  first  grade  "  or  "  first-quality  refined  turpen- 
tine." The  receivers  are  changed  at  a  certain  point  (page  58),  and 
the  distillate  which  then  comes  over  is  called  "  refined  second- 
quality  turpentine."  This  has  distilling  temperature  limits  somewhat 
higher  than  those  accepted  for  true  commercial  wood  turpentine. 
Finally,  the  receivers  are  changed  again,  the  last  of  the  distillate  be- 
ing called  "  pine-oil  fraction." 

On  refining  crude  first  turpentine  a  yield  of  approximately  80  per 
cent  of  refined  first-grade  turpentine  is  obtained,  most  of  which  dis- 
tils between  170°  and  175°  C.  From  crude  second  turpentine  the 
yield  of  refined  first-quality  turpentine  lies  in  the  neighborhood  of 
43  per  cent.  The  other  distillates  from  the  crude  turpentines  are  as 
follows:  From  crude  first  turpentine,  5J  per  cent  refined  second- 
quality  turpentine  fraction  and  7|  per  cent  pine-oil  fraction;  from 
crude  second  turpentine,  13  per  cent  refined  second  turpentine  and 
12  per  cent  pine-oil  fraction. 


38  BULLETIN   1003,   U.   S.   DEPARTMENT  OF   AGRICULTURE. 


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DISTILLATION  OF   STUMPWOOD. 


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40  BULLETIN   1003,   U.   S.   DEPARTMENT  OF  AGRICULTURE. 

PINE  OIL. 

Pine  woods  contain  oils  other  than  those  entering  into  the  composi- 
tion of  commercial  spirits  of  turpentine.  These  oils,  collectively 
spoken  of  as  pine  oil,  are  liberated  more  or  less  completely  from 
the  wood  in  their  original  form,  along  with  the  turpentine  con- 
stituents proper.  This  pine  oil  is  a  complex  substance  made  up  to 
a  large  extent  of  oxygenated  derivatives  of  the  terpenes  (turpentine 
constituents),  and  has  a  comparatively  high  boiling  point  and  spe- 
cific gravity.  The  characteristic  odor  of  pine  wood  is  due  chiefly 
to  the  presence  of  this  oil,  in  conjunction  with  turpentine.  The 
characteristic  odor  of  wood  turpentine  is  also  due  to  small  quan- 
tities of  pine  oil  present.  The  quantity  of  this  oil  recovered  is 
always  relatively  small,  varying  from  a  total  of  3£  gallons  from  a 
cord  of  very  rich  stumpwood  to  less  than  1  gallon  from  a  cord  of 
dead,  down  wood  and  poor  stumps.  It  is  necessary  to  remove  or 
separate  this  oil  as  completely  as  possible  from  the  turpentine,  be- 
cause it  does  not  evaporate  readily,  and  a  turpentine  containing  even 
a  small  percentage  of  it  will  remain  sticky  or  "tacky"  after  drying. 
Its  value  as  a  thinner  in  the  paint  and  varnish  industry  would  be 
affected  accordingly. 

The  sum  of  the  total  refined  turpentine  and  pine  oil  recovered 
from  the  crude  first  turpentine  amounts,  on  an  average,  to  92  per 
cent,  and  that  from  the  crude  second  turpentines  to  TO  per  cent.  On 
the  basis  of  the  average  yields  from  rich  and  medium  stumpwood, 
this  would  amount  to  13.5  and  7.8  gallons  a  cord  for  the  first  crude 
turpentine,  and  8.3  and  5.7  gallons  for  the  second  crude  turpentine. 
These  are  the  results  obtained  when  the  steam  distillation  is  con- 
tinued to  the  point  where  the  oil  layer  makes  up  5  per  cent  of  the 
total  distillate  coming  over  at  the  time.  By  continuing  the  distil- 
lation to  exhaustion,  or  until  no  more  oil  is  carried  over  by  the 
steam,  an  additional  5  or  8  per  cent  of  pine  oil  may  be  recovered. 
Considerations  for  economy  of  operation  did  not  warrant  the  carry- 
ing of  the  distillation  to  this  state  of  completion.  The  composition 
of  the  pine  oil  progressively  changes,  so  that  the  portion  coming  over 
at  the  close  of  the  distillation  is  heavier  than  that  passing  over 
at  the  earlier  stau 

ALKALI  RESIDUUM. 

On  prolonged  standing  the  black,  alkaline  liquid  remaining  from 
the  distillation  separates  into  an  aqueous  layer  and  a  thick,  oleagi- 
nous, soaplike  mass  which  floats  on  top  of  the  water.  This  mass 
will  be  designated  "  alkali  residuum."  Dissolved  in  the  aqueous  layer 
is  a  small  proportion  of  what  appears  to  be  creosote  bodies.  The 
alkali  residuum,  which  is  essentially  an  impure  rosin  soap,  dissolves 
in  wait -i-  to  form  a  colloidal  solution  of  great  stability  that  exhibits 


DISTILLATION   OF   STUMPWOOD.  41 

an  alkaline  reaction.  This  solution  possesses  germicidal  properties, 
the  undiluted  material  having  a  phenol  coefficient  of  0.5.  When  the 
alkali  residuum  is  decomposed  by  the  addition  of  acid  in  excess,  a 
heavy  oil  separates,  about  75  per  cent  of  which  distils  over  between 
180°  and  340°  C.  Most  of  this  distils  between  200°  and  300°  C.  The 
higher-boiling  portion  has  the  general  appearance  and  odor  of  rosin 
oil.  When  the  alkali  residuum  is  distilled  without  previous  treat- 
ment with  acid,  about  3  per  cent  of  its  volume  is  recovered  as  pine 
oil,  along  with  30  per  cent  of  water,  after  which  the  residue  remain- 
ing in  the  flask  solidifies  to  a  hard,  soaplike  mass  soluble  in  water, 
forming  a  colloidal  solution  similar  to  that  from  the  original  alkali 
residuum. 

CALCULATION    OF    YIELDS    OF    REFINED    TURPENTINE   AND 

PINE  OIL. 

A  composite  sample  of  the  refined  second-grade  turpentine  when 
dry  distilled  through  a  fractionating  column  yielded  83  per  cent  of 
turpentine  distilling  between  170°  and  185°  C.,  having  a  density  of 
0.8622  and  a  refractive  index  of  1.4736.  The  residue  from  this  dis- 
tillation was  a  true  pine  oil,  the  density  of  which  was  0.9423,  with 
a  refractive  index  of  1.4937.  A  composite  sample  of  the  pine-oil 
fractions  obtained  in  refining  first  and  second  crude  turpentines,  dis- 
tilled in  a  like  manner,  gave  40  per  cent  of  turpentine  distilling  be- 
tween 175°  and  185°  C.,  the  density  and  refractive  index  of  which  were 
0.8655  and  1.4755,  respectively.  .  The  residuum  was  also  true  pine 
oil  similar  to  that  remaining  from  the  distillation  of  the  second- 
quality  turpentine. 

The  properties  of  the  turpentine  fractions  thus  obtained  from  the 
refined  second  turpentine  and  the  pine-oil  fractions  do  not  differ 
markedly  from  those  of  the  refined  first  turpentine.  Moreover,  the 
volume  being  but  small  compared  to  that  of  the  refined  first  turpen- 
tine, it  is  believed  that  these  may  be  combined  without  materially 
lowering  the  quality  of  the  product.  The  total  merchantable  tur- 
pentine, therefore,  will  be  figured  on  the  basis  of  the  first  refined 
turpentine  plus  83  per  cent  of  the  corresponding  second  refined  tur- 
pentine and  40  per  cent  of  the  pine-oil  fraction,  respectively.  The 
sum  of  the  three  is  entered  in  the  "  merchantable  turpentine  "  column 
of  Table  14. 

On  the  same  basis,  the  volume  of  true  pine  oil  will  be  17  per  cent 
of  the  refined  second  turpentine  plus  60  per  cent  of  the  pine-oil 
fractions  obtained  in  refining  the  crude  turpentines.  The  yield  of 
pine  oil  given  in  the  "  merchantable  pine  oil "  column  of  Table  14 
is  thus  obtained.  The  sum  of  the  refined  first  and  second  turpentine 
and  pine-oil  fraction  is  not  equal  to  the  sum  of  the  first  and  second 
crude  turpentine.  The  portion  thus  unaccounted  for  is  retained  dur- 


42 


BULLETIN  1003,  U.   S.  DEPARTMENT  OF  AGRICULTURE. 


ing  the  refining  process,  partly  in  the  alkali  residuum  and  partly  in 
the  aqueous  distillate. 

A  summary  of  yields  a  cord  of  both  crude  and  refined  products 
obtained  from  each  class  of  wood  is  given  in  Table  19. 

TABLE  19. — Yields  per  cord  of  crude  and  refined  products  from  each  class  of 

wood  distilled. 


Product. 

Rich  stump- 
wood  (8 
samples). 

Medium  stump- 
wood  (6 
samples). 

Green  stump- 
wood  (2 
samples). 

Dead,  down 
wood  (4      ' 
samples). 

i 

s^ 
S* 

l_ 

6.9 
6.8 

1  Green  tops  and  limbs 
g  2  |  (1  sample). 

j 

I 

I 

'e 
> 

•§ 

i 

j 

Average. 

Maximum. 

1 

Average. 

j 

Minimum. 

•5 

Crude    first    turpentine 
(A)  gallons.. 
Crude    second    turpentine 
(B)  gallons.. 

Total  do.... 

Crude  light  oil  do.... 
Crude  heavy  oil  do 

17.1 

17.8 

13.3 
7.6 

14.9 
11.1 

12.1 
10.5 

6.8 
6.4 

9.0 
8.1 

9.9 
7.4 

8.7 
5.0 

9.3 
6.2 

17.8 
13.5 

4.5 

2.8 

8.6 
6.3 

34.9 

8.3 
70.5 
74.4 

13.3 

7.9 

21.0 

2.7 
29.5 
55.9 

===== 

10.0 
3.1 

26.0 

===== 
4.6 
46.0 
64.4 

== 

11.8 
5.0 

22.6 

—  — 

4.9 
31.7 
74.4 

==: 

9.7 
6.1 

13.5  17.1 

2.  8     3.  6 
24.4  26.5 
54.31  64.1 

5.1     7.1 

1.5     3.6 

16.1 



3.2 
32.1 
69.2 

=== 

8.1 
3.8 

14.9 

~2^5 
30.1 
63.6 

===== 

7.2 
2.5 

15.5 

" 

2.9 
31.1 
66.4 

- 

7.6 
3.2 

31.3 

4.9 
47.0 
75.8 

13.6 
2.9 

7.3 

2.8 
19.5 
53.4 

" 

14.9 

3.6 
28.6 
63.6 

6.4 
1.8 

13.7     5.9 

2.9i    3.3 
23.6    in.  1 
59.4'  80.8 

5.7     2.0 
2.8     1.1 

Acid  liquor  do  

Refined     first     turpentine 
from  A  gallons.. 
Refined,    first     turpentine 
from  B.  ..            gallons 

Total  do 

21.2 

===== 

1.3 

13.4 

== 

.6 

16.8 

•-• 

.8 

15.8 

— 

g 

JU, 
4 

10.7 
g 

11.0 

== 

7 

10.6 

- 

4 

10.8 

~ 

16.  5J    3.4 

"T" 

13        3 

8.2 
7 

8.5 
4 

3.1 
3 

Refined  second  turpentine 
from  A  gallons.. 

Refined  second  turpentine 
from  B  gallons.. 

Total  do.... 

Pine    oil    fraction  from 
A  gallons.. 
Pine     oil    fraction     from 
B  gallons.. 

Total  do.... 

Merchantable  turpentine 
gallons.. 
Merchantable  pine  oil 

2.3 

.9 

1.5 

1.5 

.9 

1.1 

1.0 

.5 

.8 

1.9|      .3 

.8 

.7 

.3 

3.0 

== 

1.7 
2.6 

1.7 

== 

.9 
1.1 

2.3 

== 

1.2 

1.5 

1.9 

== 

1.1 
1.2 

1.3 

— 

.3 

.9 

1.7 

-  —  —  •  ••" 

.     .7 
1.0 

1.4 

===== 

.5 
.5 

1.2 

.3 
.4 

1.3 

^ 

.4 

3.2 

-^-        ' 

1.6 
2.8 

.6 

.3 
.3 

1.5 

.7 
1.1 

1.1 

.3 
.6 

.6 

.2 
.3 

4.3 

=== 

25.7 

3.1 
237 
988 
3,500 

2.2 

—  •-'""• 

16.2 

1.6 
110 
670 
2,500 

2.7 



19.8 

2.0 
188 
789 
2,812 

2.1 

18.0 

1.6 
188 
800 
3,000 

1.2 

===== 

8.9 

1.0 
102 
651 
2,200 

1.7 



12.7 

1.3 
131 
711 
2,417 

.9 

" 

12.5 

.s 
144 
823 
2,500 

.8 

*_"" 

11.8 

.8 
143 
768 
2,400 

.9 

—  —  .-._.^ 

12.2 

.8 
143 
795 
2,450 

4.4 

21.0 

3.1 

104 
863 
3,000 

.6 

4.6 

.4 
42 
671 
2,000 

1.8 

10.2 

1.3 

84 
790 
2,400 

.9 

9.7 

.8 
83 
714 
2,100 

.5 

3.8 

.4 
22 
764 
2,400 

Pitch  pounds.  . 
Charcoal  do 
Cord  weights  do.... 

The  average  weight  a  cord  of  the  rich  stumpwood  is  2,612  pounds, 
as  against  2,450  pounds  for  selected  stumpwood,  and  2,412,  2,400, 
2,100,  and  2,400  pounds  for  medium  stumpwood,  dead,  down  knots 
and  limbs,  poor  stumpwood,  and  green  tops  and  limbs,  respec- 
tively. The  corresponding  yields  of  refined  first  turpentine  are  16.8, 
10.8,  10.7,  8.2,  8.5,  and  3.1  gallons  a  cord;  and  the  yields  of  total 
merchantable  turpentine  are  19.8,  12.2,  12.7,  10.2,  9.7,  and  3.8  gallons 
a  cord,  respectively.  With  the  exception  of  that  from  the  green  tops 
:in.l  limbs,  the  yield  of  turpentine  a  cord  follows  the  weight  a  cord. 
The  yields  of  pine  oil  and  crude  light  oil,  while  not  varying  greatly, 


DISTILLATION   OF   STUMPWOOD.  43 

show  the  same  tendency  to  follow  the  weight  a  cord  and  field  classi- 
fication of  the  wood.  This  tendency  is  shown  also  by  the  yield 
of  heavy  crude  oil  and  of  pitch.  The  acid  liquor  and  charcoal,  how- 
ever, are  not  subject  to  any  such  general  deductions,  although  the 
highest  yields  of  acid  liquor  are  generally  given  by  the  green  woods, 
followed  by  the  richer  stumpwood.  In  all  probability  this  is  due 
to  the  fact  that  acetic  acid  is  one  of  the  decomposition  products  of 
rosin. 

An  experienced  person  can  classify  stumps  in  the  field  into  several 
grades  from  which  the  average  yields  of  valuable  products  differ  to 
such  an  extent  as  to  necessitate  a  proper  selection  of  the  material 
before  collection. 

COMMERCIAL   DISTILLATION   PROCESSES. 

There  are  four  general  processes  for  the  recovery  of  products  from 
resinous  wood.  Two  of  these  are  destructive  distillation  processes 
and  two  are  nondestructive  extraction  processes.  They  are :  (a)  The 
common  or  ordinary  destructive  distillation  process;  (b)  the  con- 
trolled temperature  destructive  process ;  (c)  the  steam  distillation  or 
extraction  process;  and  (d)  the  solvent  extraction  process.  Of  these 
the  ordinary  destructive  distillation  process  is  the  only  one  which 
seems  to  be  well  adapted  to  the  stump-disposal  project  in  the  North- 
west. 

ORDINARY  DISTILLATION  PROCESS. 

The  wood-distilling  oven  now  in  general  use  for  the  destructive 
distillation  of  wood  is  an  outgrowth  of  the  old  charcoal  heap.  By- 
product charcoal  kilns,  round  iron  retorts,  and  rectangular  iron  or 
concrete  ovens  are  in  use,  the  rectangular  oven  being  preferred  in 
the  best  practice.  Experience  with  these  different  forms  has  taught 
that  there  is  a  mean  temperature  which  gives  the  most  satisfactory 
yields.  This  temperature  is  necessarily  more  difficult  to  maintain 
in  direct-heated  retorts,  the  smaller  of  which  have  the  further  dis- 
advantage that  the  charcoal  must  be  removed  by  hand,  necessitating 
a  loss  in  time  required  for  cooling  as  well  as  a  fuel  loss  in  reheating 
the  retort  for  the  next  charge. 

The  uneconomical  working  of  the  round  retort  has  led  to  the  de- 
velopment of  the  rectangular  oven.  Such  ovens  are  of  steel  or  con- 
crete construction  and  are  heated  either  directly  by  fires  under  them, 
in  the  case  of  the  steel  ovens,  or  by  means  of  internal-heating  flues 
in  the  concrete  ovens.  The  second  method  is  said  to  be  better 
adapted  to  softwood  distillation.  The  height  and  width  of  the  ovens 
are  uniform,  being  in  general  8  feet  4  inches  and  6  feet  3  inches,  re- 
spectively, and  the  length  ranges  from  26  to  54  feet  or  more,  accord- 


44  BULLETIN  1003,   U.   S.   DEPARTMENT  OF   AGRICULTURE. 

ing  t<>  the  desired  capacity.    An  oven  52  feet  long,  G  feet  3  inches 
wide,  and  8  feet  4  inches  high  holds  10  cords  of  wood. 

The  charge  of  wood,  of  regular  con  1  wood  size,  is  loaded  onto 
steel  tramcurs  of  special  construction  and  hauled  into  the  retort  or 
oven,  which  is,  of  course,  tightly  closed  during  the  distillation.  At 
the  end  of  this  operation,  the  train  of  cars  bearing  the  still  hot 
charcoal  is  hauled  out  into  the  cooling  shed  of  sheet  iron,  where  the 
charcoal  cools  down  without  loss  of  fire.  Simultaneously,  another 
trainload  of  wood  enters  the  oven,  and  the  new  distillation  proceeds 
with  a  minimum  heat  loss. 

In  addition  to  the  ovens,  coolers,  cars,  and  necessary  brickwork  or 
the  setting  of  the  ovens,  condensers,  which  should  be  of  ample  ca- 
pacity to  handle  the  distillate  under  the  most  unfavorable  operating 
conditions,  will  be  required,  as  well  as  stills,  steel  tanks  to  hold  the 
product,  wooden  tanks,  pumps,  generators,  steam  boilers  and  engine, 
yard  tracks,  piping,  etc.,  and  the  necessary  buildings  for  housing  the 
plant. 

A  conservative  estimate  of  the  cost  of  such  a  plant  is  between 
$4,000  and  $5,000  a  cord  capacity.  Before  the  war  these  plants  could 
be  built  for  from  $1,500  to  $3,000  a  cord  capacity,  or  at  a  total  cost, 
including  working  capital,  of  approximately  $20,000  for  a  10-cord 
.plant.  The  cost  of  construction  and  of  operation  and  the  design  and 
character  of  the  equipment  "will  vary,  and  quite  widely,  with  the  pro- 
posed location  of  the  plant  and  the  work  it  is  to  do,  and  with  the 
experience  and  practice  of  the  designing  and  constructing  engineers. 
For  these  reasons,  no  details  of  equipment  or  specifications  are  given. 
This  information  can  best  be  secured  from  wood-distillation  engi- 
neers and  from  builders  of  the  equipment,  whose  advertisements  ap- 
pear in  the  various  industrial  journals.  The  Bureau  of  Chemistry 
can  furnish  a  list  of  engineers  and  builders  of  wood-distilling  plants. 


CONTROLLED  TEMPERATURE  PROCESS. 


The  controlled  temperature  or  circulating  oil  process  and  retort 
have  been  fully  described  in  the  preceding  pages.  Even  on  a  com- 
mercial scale  a  prerequisite  of  this  process  is  that  the  pieces  of  wood 
be  relatively  smaller  in  diameter  than  those  used  in  the  ordinary  de- 
structive process,  to  insure  rapid  distillation.  When  properly  car- 
ried out,  better  separation  of  the  several  products  of  distillation  is 
obtained,  with  the  result  that  the  turpentine  ordinarily  obtained  com- 
mands a  slightly  higher  price  (3  to  5  cents  a  gallon)  for  paint  or 
varnish  purposes  than  the  turpentine  produced  by  the  regular  de- 
strnctive  process,  in  which  the  temperature  is  not  definitely  con- 
trolled. While  tliis  process  yields  a  better  grade  of  wood  turpentine, 
the  equipment  and  upkeep  are  more  expensive,  and  greater  skill  and 


DISTILLATION   OF   STUMPWOOD.  45 

a  larger  force  are  required  in  operating  than  for  the  uncontrolled 
process.  For  this  reason  it  is  rarely  used  for  distilling  resinous 
wood. 

STEAM   DISTILLATION    PROCESS. 

The  steam  distillation  process  requires  that  the  wood  to  be  ex- 
tracted shall  be  finely  divided  by  chipping  or  shredding  before  treat- 
ment ;  the  finer  the  chips,  the  more  rapid  and  complete  the  extraction. 
For  this  reason  the  steam  process  has  been  installed  by  several  saw- 
mills for  the  recovery  of  turpentine  from  sawdust.  The  best  results 
are  not  obtained  with  all  dust,  however,  as  it  packs  so  tightly  that 
the  steam  is  kept  from  penetrating  throughout  the  entire  mass  to  be 
extracted.  Chips  of  a  size  passing  an  inch  and  retained  by  a  quarter- 
inch  screen  are  desirable,  and  a  limited  amount  of  sawdust  can  be 
mixed  with  such  chips. 

Few  plants,  other  than  lumber  mills  where  the  production  of  wood 
turpentine  and  pine  oil  is  only  a  side  issue,  have  continued  to  operate 
on  the  steam  process  alone,  and  have  invariably  closed  when  turpen- 
tine sold  at  less  than  50  cents  a  gallon.  The  turpentine  produced  by 
this  method  is  of  high  quality,  approaching  that  made  by  the  regular 
distillation  from  gum.  The  practicability  of  maintaining  a  steam 
distillation  plant  depends  entirely  on  market  conditions ;  if  the  price 
of  turpentine  is  sufficiently  high  the  steam  method  will  be  a  paying 
proposition.  The  steam  distillation  outfit  is  now  usually  installed  in 
conjunction  with  a  solvent  plant  that  can  extract  the  residual  wood 
chips  for  the  recovery  of  rosin  and  certain  of  the  heavier  pine  oils. 

SOLVENT  EXTRACTION   PROCESS. 

In  the  solvent  process  also  the  wood  must  be  finely  divided.  This 
process  is  one  where  the  wood  is  extracted  in  large,  tight  digesters 
at  a  relatively  high  temperature  by  means  of  suitable  volatile  sol- 
vents, the  choice  of  which  is  determined  mainly  by  price.  Gasoline, 
coal  tar,  naphtha,  or  turpentine  can  be  used,  gasoline  being  the  one 
in  common  use.  When  the  solvent  is  added  in  the  beginning  of  the 
operation,  that  is,  with  no  previous  steam  distillation,  all  of  the  solu- 
ble pine  products  are  removed  altogether,  and  the  resulting  mixture 
is  fractionated  to  recover  the  naphtha  or  other  solvent  and  to  sepa- 
rate the  turpentine  and  pine  oils  from  the  rosin.  The  rosin  obtained 
in  this  way  is  not  so  free  from  tackiness  as  pure  gum  rosin,  and  has 
a  rather  darker  color,  but  is  quite  clear  when  properly  made.  Fur- 
thermore, it  is  very  difficult  to  remove  the  solvent  completely  from 
the  turpentine.  It  has  been  found  advantageous,  therefore,  to  com- 
bine the  steam  and  solvent  processes,  the  only  objection' to  this  being 
that  the  steam  leaves  the  chips  in  a  moist  condition,  in  which  state 
the  extraction  does  not  take  place  as  readily  as  if  they  were  abso- 
lutely dry. 


46  BULLETIN   1003,   U.   S.   DEPARTMENT  OF  AGRICULTURE. 

BATH  PROCESS. 

An  advantage  of  the  bath  process,  another  method  which  has  been 
used  to  a  limited  extent,  is  that  the  wood  does  not  require  previous 
shredding.  The  wood  is  run  into  the  retort  on  cars,  and  the  retort 
is  flooded  with  a  high-boiling  material, 'such  as  molten  rosin,  pitch, 
or  tar,  heated  to  a  sufficiently  high  temperature.  Most  of  the  ex- 
tracted turpentine  and  pine  oils  are  volatilized  at  the  temperature 
of  the  bath,  and  the  rest  is  blown  out  of  the  bath  with  steam.  The 
remaining  wood,  which  is  saturated  with  the  rosin  or  other  material 
of  the  bath,  may  be  destructively  distilled  to  recover  the  light  and 
heavy  crude  oils,  tar,  charcoal,  and  pitch. 

FEASIBILITY  OF  DISTILLING  WESTERN  YELLOW  PINE. 

Yellow-pine  stumps  of  a  quality  such  as  to  yield  more  than  12J 
gallons  a  cord,  the  average  yield  from  medium-grade  stumpwood, 
of  merchantable  wood  turpentine,  of  the  properties  shown  in  Table 
18,  and  other  products  in  corresponding  proportion,  are  compara- 
tively scarce.  "  Fat  "  or  "  pitchy  "  stumps,  averaging  20  gallons  of 
merchantable  turpentine  a  cord,  are  not  sufficiently  numerous  to  be 
considered  in  a  class  by  themselves  as  an  impediment  to  land-clearing 
operations,  and  would  need  to  be  hauled  for  long  distances  in  supply- 
ing wood  to  distilling  plants. 

The  daily  yield  from  a  10-cord  plant  and  the  market  value  of  the 
products  from  the  rich  portion  of  medium-grade  stumps,  based  on 
the  yields  obtained  in  these  experiments  and  on  the  prevailing  eastern 
prices  June,  1918,  using  the  ordinary  ovens  in  general  use,  would  be 
approximately  as  follows: 

Merchantable  turpentine 127  gallons  @  $0.  50 $63.  50 

Pine  oil 13      do.      @      .40 5.20 

Light  oil  (at  tar  oil  prices) 35      do.       @       .20 7.00 

Heavy  oil  (at  tar  prices) 275      do.      (6  barrels)  @  $0.15 41.25 

Pitch 7  barrels  ( 1,400  pounds )  @  $3.50_.    24.50 

Charcoal 350 bushels  (7,110 pounds)  @  $0.12_      42.00 


183.  45 
Total  value  of  products  a  cord  of  selected  medium-grade  resinous 

wood  or  heartwood .$18.  36 

The  average  yield  and  market  value  of  the  products  recovered 
from  a  cord  of  rich  stumpwood  on  the  same  basis  are  estimated  to  be : 

Merchantable  turpentine 19.8  gallons  @  $0.50 $9.90 

Pine    oil 2.0      do.       @       .40 .80 

Light  oil 4.5      do.       @       .20 .90 

Heavy  oil 46. 0      do.       @        15 0. 90 

Pitch .  138. 0  pounds  @     3.  50  a  barrel 2.  41 

Charcoal 38.  0  bushels  (790.0  pounds)  @  $0.12.    4.56 

<          Total  value  of  products  a  cord 25.  47 


DISTILLATION   OF   STUMPWOOD. 


47, 


These  yields  and  values  are  comparable  to  those  obtained  in  dis- 
tilling longleaf-pine  lightwood  in  the  South  Atlantic  States,  as  shown 
by  the  following  figures,  taken  from  Bureau  of  Chemistry  Bulle- 
tin 144 : 

Products  from  1  cord  (4,000  pounds)  of  longleaf  yellow-pine  lightwood  (destruc- 
tive process). 

Total  crude  oil - gallons__  36  to  120 

Refined  wood  turpentine do 5  to    20 

Pine  oils do 2  to      5 

Rosin  oil do 20  to    65 

Light  and  heavy  oils : 

Creosote gallons—    8  tQ    20 

Rosin  spirits do 2  to     10 

Charcoal bushels__  30  to     50 

Cost  of  operating  per  day  and  per  cord  (1915  figures). 

10  cords  of  wood,  at  $8.37  a  cord,  delivered $83. 70 

Fuel  wood,  in  addition  to  gases  and  fine  charcoal,  10  cords,  at  $2.50  a 

cord,  delivered 25. 00 

Labor,  8  men  (3  shifts),  at  $2.50  a  day  (average  wage) 20. 00 

Technically  trained  works  manager,  at  $125  a  month 4. 15 

Depreciation,  at  15  per  cent  of  investment  in  plant  ($20,000) 8.  20 

Upkeep,  at  8  per  cent  of  investment  in  plant  ($20,000) 4.40 

Insurance,  at  3  per  cent  of  investment  in  plant  ($20,000)  (average) 1. 65 

Chemicals  for  still  house,  etc 1. 00 

Barrels  or  other  containers  for  making  deliveries 15. 00 

Interest  on  total  investment  ($25,000),  at  6  per  cent 4. 11 

167.  21 

Total  daily  production  cost,  exclusive  of  sales  or  marketing  ex- 
penses, a  cord 16.  72 

Marketing  expenses,  although  an  important  item,  are  not  included, 
because  they  depend  largely  on  the  business  policy  of  the  manage- 
ment and  upon  competition. 

The  cost  of  operating  a  plant  in  the  South  Atlantic  States  is 
but  little  more  than  half  this  estimate,  because  of  the  much  lower 
cost  of  wood  and  of  labor  in  the  South.  If  the  medium-grade  wood 
could  be  distilled  at  the  usual  southern  cost,  it  would  yield  a  fair 
return.  The  approximate  cost  of  operating  a  destructive  distil- 
lation plant  in  the  South  Atlantic  States  is  as  follows : 

Cost  of  wood  for  distilling,  a  cord $1.  50  to  $3. 00 

Management,  labor,  fuel,  packing,  a  cord 2.  50  to    6. 00 

Interest  and  depreciation,  a  cord .  60  to     1.  60 


Total 4.60  to  10.60 

The  values  assigned  to  the  several  products  are  representative  of 
those  prevailing  on  the  eastern  coast  shortly  after  the  European 
war  started.  To  this  must  be  added  the  cost  of  transportation  to 


48  BULLETIN   1003,   U.   S.   DEPARTMENT  OF   AGRICULTURE. 

the  West  and  western  dealers'  profits,  which  were  not  included  for 
the  reason  that  they  vary  greatly,  and  also  because  local  freight 
rates  to  interior  points  would,  in  many  instances,  be  nearly  as  great 
from  western  points  to  consuming  points  as  the  through  rates  from 
the  South  to  the  same  consuming  points.  Since,  in  any  event,  sin -h 
competitive  freight  charges  would  vary  greatly  with  the  locality, 
they  are  not  included  in  the  estimation  of  values  here  given,  but 
they  must  receive  very  careful  consideration  before  the  erection 
of  a  plant  for  the  recovery  of  products  from  wood. 

On  the  basis  of  the  foregoing  carefully  considered  and  conserva- 
tive estimates  of  cost  of  production  and  of  the  value  of  products,  it 
must  be  concluded  that  stumps  of  medium  quality,  giving  the  aver- 
age yields  stated,  can  not  be  profitably  utilized  generally  by  the 
destructive  distillation  methods.  Needless  to  state,  if,  because  of 
exceptionally  favorable  local  conditions,  the  cost  of  wood  at  the 
plant  can  be  materially  reduced,  wood  of  medium  richness  could  be 
profitably  distilled.  Such  localities  should  be  given  very  thoughtful 
and  systematic  consideration  by  experienced  and  practical  distilla- 
tion experts  before  undertaking  their  exploitation. 

Since  poor  stumps  and  dead,  down  wood  contain  even  less  resin- 
ous matter  than  the  medium  stumps,  they  could  not  be  profitably 
distilled. 

On  the  other  hand,  the  rich  or  pitchy  stumps  contain  enough 
resins  to  make  their  distillation  profitable  in  those  localities  where 
they  are  sufficiently  numerous.  With  wood  containing  enough  resin- 
ous matter  to  average  the  yields  given  for  rich  stumpwood,  obtain- 
able at  even  $10  a  cord,  a  wide  margin  of  profit  is  possible  by  the 
process  outlined,  provided  all  the  products  can  be  marketed  at  prices 
not  materially  lower  than  those  used  in  the  foregoing  estimate.  To 
maintain  an  adequate  wood  supply  of  this  quality,  sufficient  for  a 
plant  to  operate  a  number  of  years,  it  will  be  necessary  to  resort  to 
a  long-distance  railroad  haul  and  long-distance  wagon  transporta- 
tion to  railroad  sidings.  For  this  reason,  a  cost  of  something  like 
$10  a  cord  should  be  allowed  in  estimates  for  such  wood,  the  cost  of 
getting  out  the  stumps  alone  exceeding  $6.  The  possibility  of  ob- 
taining at  reasonable  prices  sufficient  quantities  of  rich  stumps  which 
are  thinly  distributed  over  the  land,  entailing  a  high  cost  of  collect- 
ing, is  the  vital  point  in  considering  the  practicability  of  wood  dis- 
tillation in  the  Pacific  Northwest. 

The  impression  that  more  material  than  that  obtained  from  the 
rich  stumps  might  be  drawn  on,  because,  the  margin  of  profit  for 
this  material  appearing  quite  large,  an  appreciable  proportion  of 
wood  intermediate  in  quality  between  that  from  rich  and  that  from 
medium-grade  stumps  combined  with  the  rich  grade  would  give  a 
material  worth  working  up.  would  in  general  be  misleading. 


DISTILLATION   OF  STUMPWOOD.  49 

When  stumps  of  the  different  grades  (p.  15)  were  dynamited 
but  little  difference  was  found  between  the  poor  and  medium-quality 
stumps.  Furthermore,  unless  the  exudation  of  rosin  is  exception- 
ally abundant,  it  can  not  be  taken  as  an  indication  that  the  stumps 
are  rich  or  pitchy.  So  disappointing  was  this  superficial  indication 
of  quality,  used  before  its  true  value  was  established  from  dyna- 
miting a  number  of  stumps,  that,  to  avoid  shipping  a  lot  of  what 
was  plainly  worthless  material,  the  poor  stumps  were  taken  from 
those  that  had  been  classified  as  medium,  leaving  only  a  few  spe- 
cially selected  stumps  from  which  the  rich  wood  proper  was  ob- 
tained. 

In  view  of  these  facts,  poor  and  medium-quality  stumps,  as  the 
terms  are  used  in  this  bulletin,  are  those  in  which  the  sound  heart- 
wood  approximately  equals  in  resinous  .appearance  that  found  in 
the  heartwood  of  an  average  yellow-pine  log,  except  that  it  is  richer 
toward  the  spreading  of  the  roots.  The  resinous  material  in  such 
wood  comes  largely  from  this  portion  of  the  stump.  Medium 
stumps  differ  from  poor  stumps  only  in  that  there  is  a  somewhat 
larger  proportion  of  the  very  resinous  wood  at  the  spreading  of  the 
roots,  the  main  volume  of  heartwood  in  these  two  classes  of  stumps 
appearing  to  be  essentially  alike.  Rich  or  pitchy  stumps  differ  from 
the  medium  in  that  the  heartwood  is  more  uniformly  resinous 
throughout  the  whole  of  the  stump  and  constitutes  perhaps  from 
60  to  80  per  cent,  or  more,  of  the  whole  stump,  while  in  the  poor 
and  medium  stumps  the  resinous  portion  constitutes  less  than  half 
of  the  entire  stump. 

To  verify  the  conclusion  that  the  rich  or  pitchy  stumps  average 
not  more  than  a  cord  an  acre  of  wood  suitable  for  distillation,  all 
the  stumps  on  a  typical  area  were  removed,  representative  samples 
selected,  and  an  estimate  made  of  the  total  quantity  of  such  wood 
on  the  area  from  which  stumps  were  taken.  This  selected  represen- 
tative acre  contained  12  stumps,  9  of  which  were  classed  as  medium 
to  poor,  and  3  as  resinous  or  rich.  The  9  nonresinous  stumps  con- 
tained between  3  and  4  cords  of  wood,  of  which  but  1,500  pounds,  or 
one-half  cord,  was  sound  heartwood,  the  remainder  being  doaty, 
nonresinous  sapwood,  which  was  separated  from  the  heartwood  in 
the  field,  only  the  heartwood  being  taken  to  the  laboratory.  At 
least  80  per  cent  of  worthless  nonresinous  material  was  split  out 
of  these  stumps  in  obtaining  the  half  cord  of  heartwood.  In  the 
large  resinous  stumps  there  were  1J  cords  of  resinous  wood,  all  of 
the  quality  represented  by  the  sample.  The  nonresinous  stumps, 
though  quite  large  (36  to  40  inches),  were  smaller  than  the  resinous 
stumps. 

60953°— 21 4 


50  BULLETIN  1003,   U.   S.   DEPARTMENT  OF  AGRICULTURE. 

The  wood  selected  from  that  classed  as  the  less  resinous  stumps 
was  richer  than  that  from  the  3  rich  stumps.  Weight  for  weight 
of  material  in  the  selected  samples  this  is  true.  However,  of  the 
wood  running  18  gallons  of  turpentine  a  3,000-pound  cord,  only 
about  1,500  pounds,  or  one-half  cord,  in  the  entire  lot  of  9  stumps 
contained  an  estimated  volume  of  3  or  4  cords  of  wrood.  To  run  all 
of  this  wood  would  eliminate  the  cost  of  splitting  out  the  resinous 
wood  from  the  sapwood.  It  would,  however,  quadruple  the  cost 
of  rail  and  wagon  haul  and  the  time  and  cost  of  distilling,  and,  at 
the  same  time,  would  cut  down  the  yield  to  about  5  gallons  a  cord 
of  very  inferior  turpentine,  with  a  proportional  reduction  in  other 
products. 

The  half  cord  of  resinous  wood  from  the  9  stumps,  combined  with 
that  from  the  3  more  resinous  stumps,  gave  about  2  cords  of  wood, 
running  17  gallons  of  turpentine  a  cord.  Had  all  the  wood  on  the 
acre  plot  been  used,  there  would  have  been  6  cords,  yielding  not 
more  than  6  or  7  gallons  of  turpentine  a  cord,  with  the  other  prod- 
ucts in  like  proportions.  Neither  the  results  of  these  experiments 
nor  the  wood-distillation  practices  in  the  South  warrant  the  belief 
that  wood  of  this  quality  can  be  profitably  distilled.  It  is  better  to 
split  out  and  reject  the  low-grade  wood. 

While  a  large  proportion  of  the  yellow-pine  stumps  in  Idaho  con- 
tain a  certain  amount  of  resinous  wood  which  is  as  rich  as  the  truly 
pitchy  stump,  such  wood  forms  so  small  a  proportion  of  the  entire 
stump  that  its  removal  from  the  nonresinous  wood  is  prohibitively 
expensive.  The  case  is  similar  to  that  of  many  ore-bearing  forma- 
tions in  which  the  valuable  mineral  is  disseminated  through  so  large 
a  proportion  of  worthless  material  as  to  make  its  concentration  in  a 
form  rich  enough  for  treatment  commercially  impracticable. 

At  the  1915  prices  for  raw  material  and  for  products,  wood  from 
60  to  80  per  cent  of  which  must  be  split  off  and  rejected,  or  wood 
which  will  yield  but  6  gallons  of  turpentine  or  a  total  of  30  gallons 
of  resinous  products  a  cord,  could  not  be  profitably  distilled.  When 
the  nonresinous  portion  of  the  stumps  has  rotted  away,  leaving  only 
the  resinous  heart,  this  material,  which  then  would  be  similar  to  the 
rich  stumps,  could,  of  course,  be  profitably  used,  provided  the  ratio 
of  cost  to  selling  value  remained  essentially  the  same. 

Future  careful  studies  of  the  uses  to  which  the  heavy  crude  oil 
may  be  put  probably  will  result  in  a  revision  of  the  price  here  as- 
signed to  it.  That  of  15  cents  a  gallon  is  based  on  its  probable  value 
for  uses  to  which  certain  of  the  creosote  oils  are  being  put.  Undoubt- 
edly its  value  can  bo  enhanced  by  suitable  refining  methods,  or  by 
working  it  up  into  special  products.  These  would  necessitate  addi- 
tional equipment  and  labor,  thus  increasing  the  manufacturing  cost, 
the  probable  expediency  of  which  can  not  be  foretold.  The  same  con- 


DISTILLATION   OF   STUMPWOOD.  51 

sideration  applies  to  the  light-oil  fraction.  From  the  prevailing  price 
of  articles  with  which  such  refined  or  special  products  must  compete, 
it  is  doubtful  if  the  balance  between  production  cost  and  market  value 
of  the  output  of  a  plant  would  be  materially  affected  thereby. 

The  acetone,  wood  alcohol,  and  acetic  acid  content  of  the  aqueous 
distillate  is,  roughly,  one- fourth  that  obtained  in  the  crude  distillate 
from  hardwood  plants.  The  value  a  cord  of  the  alcohol  and  acetic 
acid  recovered  as  acetate  of  lime,  based  on  1915  prices,  is  approxi- 
mately $1  and  $1.50,  respectively.  The  crude  liquor  as  obtained  from 
the  retorts  is  so  heavily  charged  with  tarry  bodies  that  the  acetate  if 
obtained  therefrom  by  the  ordinary  method  is  of  a  low  grade  and 
at  best  usually  commands  too  low  a  figure  to  make  its  recovery  profit- 
able. Even  by  some  improved  processes,  the  recovery  of  these  three 
products,  which  would  increase  the  gross  income  by  about  $2.50  a  cord, 
could  be  accomplished  at  best  only  on  a  narrow  margin  of  profit, 
and  the  earning  power  of  a  plant  thus  equipped  would  not  be  ma- 
terially increased  by  so  doing.  A  company  in  the  Northwest,  oper- 
ating a  wood- distilling  plant  on  selected  Douglas  fir  mill- waste,  in- 
cluding the  recovery  of  these  products  in  their  margin  of  profits, 
found  the  enterprise,  as  then  carried  out,  unprofitable. 

One  other  possibility  needs  to  be  mentioned.  It  has  been  stated 
that  lean  and  also  medium  resinous  stumps  contain  small  propor- 
tions of  heartwood  nearly  if  not  quite  as  rich  in  resin  as  the  resinous 
portions  of  rich  stumps,  but  the  proportion  of  such  wood  is  so  small 
that  the  cost  of  splitting  it  out  would  be  prohibitive.  Should  the 
nonresinous  portion  rot  off  the  lean  and  medium  stumps  in  the 
course  of  a  few  years,  as  happens  in  the  longleaf  yellow-pine  cut- 
over  lands,  the  remainder  or  heart  of  the  stump  would  then  be  prac- 
tically 100  per  cent  resinous  and  suitable  for  distillation.  Unfortu- 
nately, few  such  rotted  stumps  showing  only  the  sound,  rich  heart 
were  observed  in  any  of  the  districts  visited.  The  rotting  off  of  the 
sapwood  would  unquestionably  proceed  more  rapidly  farther  south. 

RELATION  OF  WOOD  DISTILLATION  TO  LAND  CLEARING. 

One  of  the  purposes  of  this  investigation  was  to  secure  informa- 
tion on  what  part  of  the  cost  of  clearing  land  for  farm  purposes 
might  be  paid  for  by  distilling  the  wood  or  by  selling  the  wood  for 
distillation. 

The  cost  of  clearing  land  for  farming  in  the  Pacific  Northwest 
varies  widely,  depending  on  the  size,  number,  and  age  of  the  stumps, 
the  lay,  nature,  and  water  content  of  the  soil,  cost  of  labor  and  ma- 
terials, and  other  factors.  The  United  States  Department  of  Agri- 
culture, in  cooperation  with  the  State  agricultural  experiment  sta- 
tions of  Washington,  Wisconsin,  and  Minnesota  (11),  and  the  Uni- 


52  BULLETIN   1003,   U.   S.   DEPARTMENT  OF   AGRICULTURE. 

versity  of  Idaho  (8),  have  done  much  actual  work  on  land  clearing 
in  this  section,  and  have  found  the  cost  of  clearing  for  farm  purposes 
to  vary  from  $50  for  the  lightest  clearing  ground  to  $150  an  acre  for 
heavily  wooded  hardwood  land. 

In  the  sections  from  which  samples  were  collected  20  yellow-pine 
stumps  to  the  acre  is  a  high  average  on  land  where  the  stand  is 
mostly  or  entirely  yellow  pine ;  under  more  commonly  occurring  con- 
ditions in  which  there  is  more  of  a  mixed  stand,  such  as  in  the  Pot- 
latch-Deary  district,  10  to  12  yellow-pine  stumps  to  the  acre  is  more 
nearly  correct. 

If,  as  indicated  by  these  investigations,  10  per  cent  of  the  yellow- 
pine  stumps  are  of  the  rich,  resinous  type,  yielding  20  gallons  of 
turpentine  and  other  products  in  proportion  a  cord,  or  15,4  gallons  a 
ton,  the  12  stumps  an  acre  would  yield  1  cord,  and  20  stumps  about 
2  cords  of  wood  an  acre. 

If  the  wood  could  be  disposed  of  for  $10  a  cord,  the  return  for  the 
extra  labor,  time,  and  expense  required  to  split  and  sort  out  the 
resinous  wood  and  haul  it  to  a  shipping  point  would  be  from  $10  to 
$20.  Experiments  in  clearing  1  acre  carrying  12  yellow-pine  stumps. 
varying  from  2  to  5  feet  in  diameter  (page  18),  have  shown  that 
this  return  will  a  little  more  than  pay  for  the  powder  needed  to 
blast  out  all  the  yellow-pine  stumps.  In  other  words,  provided  a 
market  for  the  wood  at  $10  a  cord  is  available,  the  net  cost  of  land 
may  be  reduced  from  (>J  to  40  per  cent,  less  the  cost  of  sorting  and 
hauling  to  a  shipping  point. 

The  chief  question  is  whether  a  farmer  can  afford  to  shoot  all  the 
yellow  pine  clear  of  the  ground,  or  crack  with  explosives  and  pull 
the  pieces  with  a  puller,  then  sort  the  wood  and  haul  it  to  the  rail- 
road, or  whether  he  can  get  his  land  cleared  more  cheaply  by  using 
some  of  the  methods  of  burning  described  in  Idaho  Agricultural  Ex- 
periment Station  Bulletin  91,  or  United  States  Department  of  Agri- 
culture Farmers'  Bulletin  974.  If  the  returns  from  the  fat  stumps 
on  a  tract  are  sufficient  to  justify  the  more  expensive  methods  of 
clearing,  and  it  is  some  advantage  to  have  all  the  roots  out  of  the 
ground,  blasting  is  the  method  which  will  be  most  used. 

About  100  pounds  of  explosive  would  be  required  to  shoot  clear  of 
the  ground  all  the  yellow-pine  stumps  on  an  acre,  while  25  pounds 
would  crack  them  enough  so  that  they  could  be  bunted.  In  the  first 
case,  the  cost  of  explosive  (1914-15)  would  be  about  $15  and  in  the 
second  case  $4.  The  explosive  could  be  placed  with  a  little  loss  work 
if  the  stumps  were  to  be  burned.  Possibly  it  would  require  about  the 
same  amount  of  labor  to  burn  the  stumps  in  the  ground  as  it  would 
to  sort  over  the  pieces,  burn  those  unfit  for  distillation  purposes,  and 
haul  the  rest  to  the  railroad.  On  the  assumption  that  it  would,  it 


DISTILLATION   OF   STUMPWOOD.  53 

will  be  seen  that  the  farmer  would  just  about  break  even  if  he  could 
sell  the  rich  wood  for  $11  an  acre. 

A  wood- distilling  plant  of  any  size  can  not  operate  profitably  with- 
out an  ample  and  steady  supply  of  rich  wood  extending  over  a  num- 
ber of  years.  For  this  reason  a  wood-distilling  plant  should  be  built 
and  conducted  as  an  independent  business  rather  than  primarily  as 
a  means  of  meeting  the  cost  of  land  clearing.  Naturally,  it  would 
be  located  with  reference  to  available  material ;  that  is,  where  there 
was  land  ready  to  be  cleared.  Such  wood  as  the  settlers  could  supply 
would  be  simply  an  addition  to  the  stock,  though  in  some  instances 
the  bulk  of  the  wood  might  be  obtained  from  this  source. 

In  the  Winchester  and  Craig  Mountain  country,  where  the  condi- 
tions are  quite  different  from  those  observed  in  the  other  sections, 
there  is  a  close  almost  pure  stand  of  yellow  pine.  As  there  are  no 
heavy  underbrush  or  slashings,  clearing  such  cut-over  lands  consists 
practically  entirely  in  burning  the  tops  of  the  cut  trees  and  removing 
about  20  large  yellow-pine  stumps. 

The  comparative  absence  of  younger  growth  between  the  trees, 
fairly  even  surface  of  the  country,  and  uniform  stands,  of  which  per- 
haps 40  per  cent  of  the  stumps  are  quite  rich  or  resinous,  make  such 
sections  possible  localities  in  which  the  cost  of  land  clearing  may  be 
met,  in  a  large  part  at  least,  if  not  entirely,  by  distilling  the  stumps. 

SMALL,  SEMIPORTABLE  WOOD-DISTILLING  PLANTS. 

Wood-distilling  plants  as  usually  constructed  where  the  daily 
capacity  varies  from  10  to  100  <3ords  of  wood,  are  permanent, 
especially  when  a  number  of  products  are  made  and  refined  for  mar- 
ket. Furthermore,  such  plants  require  capital  for  financing  and 
technical  skill  and  experience  for  profitable  operation.  Therefore, 
wood-distilling  plants  would  be  comparatively  few,  and  small  plants 
of  about  1-cord  capacity  that  can  be  set  up,  torn  down,  and  re- 
located at  will  would  be  useful,  particularly  in  sections  removed  from 
railroads  and  where  transportation  is  difficult.  Especially  would 
this  be  true  if  the  mixed  crude  oil  and  tar  obtained  could  be  profitably 
disposed  of  to  refiners  or  directly  to  users. 

Since  the  work  described  in  this  publication  was  completed,  private 
companies  have  built  and  operated  such  small  plants.  Plants  of 
this  kind,  of  1-cord  capacity,  can  be  built  for  from  $3,500  to  $4,500. 
They  might  be  bought  and  operated  by  a  community,  the  crude  oil 
being  sold  direct  to  the  zinc,  lead,  and  copper  miners,  who  use  it 
for  the  concentration  of  ores  by  the  flotation  process.  The  cheap, 
semiportable  1-cord  retort  is  probably  better  adapted  to  Northwest 
conditions  than  are  the  large,  more  permanent,  and  more  expensive 
plants  making  and  refining  a  number  of  products. 


54  BULLETIN   1003,   U.   S.   DEPARTMENT  OF  AGRICULTURE. 

USE  OF  OIL  FOR  ORE  FLOTATION. 

Of  the  many  oils  that  have  come  into  use  for  ore  flotation,  oil 
of  eucalyptus,  costing  about  $1.50  a  gallon,  is  prized  most  highly. 
Next  in  the  order  of  merit  come  the  pine  oils,  selling  for  from  40 
to  60  cents  a  gallon.  In  the  effort  to  discover  cheaper  oils,  most  of 
the  wood  creosotes,  as  well  as  many  coal-tar  creosotes,  have  been 
found  to  be  acceptable.  They  range  in  price  from  15  to  30  cents  a 
gallon.  Producers  of  petroleum  have  also  entered  the  flotation  field, 
though  with  but  limited  success  when  petroleum  alone  is  used. 
Better  results  are  obtained  by  mixing  a  small  amount  of  pine  or 
creosote  oil  with  the  crude  petroleum.  "Kerosene  sludge  acid" 
from  California  oils,  obtained  by  treating  the  crude  oil  with  sul- 
phuric acid  in  the  refining  process,  is  also  being  sold  for  flotation. 
The  sludge  acid  from  coal  tar  is  said  to  have  a  flotation  value  as 
good  as  or  better  than  that  from  petroleum,  and  even  coal  tar  itself 
is  extensively  used  because  of  its  low  price. 

These  different  products  entering  into  ore  flotation  may  be  divided, 
in  a  general  way,  into  two  classes,  known  as  "  frothing  agents," 
which  promote  foaming,  and  "collecting  agents,"  the  function  of 
which  is  to  coat  with  a  film  of  oil  the  mineral  particles  only,  so 
that,  adhering  to  the  air  bubbles  in  the  foam,  they  are  thus  sepa- 
rated from  the  gangue.  While  all  oils  possess  both  frothing  and 
oiling  or  collecting  properties  in  some  degree,  eucalyptus  oil,  the 
pine  oils,  pine-tar  oils  (the  "light"  and  "heavy"  oils  of  this  pub- 
lication), and  crude  turpentine  are  primarily  used  as  frothing  agents. 
Coal  tar,  pine  tar,  together  with  hardwood  tar,  and  "  sludge  acid  " 
are  used  as  collecting  agents.  Success  in  ore  flotation  demands  a 
proper  adjustment  of  these  two  physical  properties  to  the  particu- 
lar requirements  of  the  ore  to  be  treated.  While  all  of  the  products 
mentioned  can  be  used  in  proper  combination,  with  some  measure  of 
success,  the  pine  oils  occupy  a  commanding  position  in  the  field  of 
ore  flotation. 

Samples  of  pine  oil  and  of  the  crude  distillates  obtained  in  the 
retort  work  were  submitted  for  flotation  tests  to  the  Bureau  of 
Mines  Metallurgical  Experiment  Station,  Salt  Lake  City,  Utah,  to 
ore  mills  in  the  Coeur  d'Alene  district,  and  to  the  testing  department 
of  a  large  copper  mining  company.  The  results  from  their  tests 
showed  that  the  crude  turpentine  was  virtually  as  effective  a  flota- 
tion agent  as  the  pine  oil,  and  even  the  light  and  heavy  oils  were 
applicable,  though  requiring  a  greater  proportion  a  ton  of  slime, 
especially  in  the  case  of  the  heavy  oil.  Even  the  acid  liquor  was 
found  useful  on  certain  pyrite  ores. 

Where,  therefore,  the  efforts  of  the  producers  were  formerly  di- 
rected toward  refining  the  crude  distillate  to  recover  a  maximum 


DISTILLATION   OF   STUMPWOOD. 


55 


quantity  of  turpentine,  the  change  in  market  conditions  makes  it 
desirable  to  throw  as  much  of  it  into  the  pine-oil  fraction  as  is 
possible,  or  to  go  a  step  farther  and  market  the  entire  crude  dis- 
tillate as  flotation  oil.  If  this  were  done  it  would,  of  course,  re- 
duce decidedly  the  cost  of  running  the  plant,  and  simplify  opera- 
tion. The  consequent  reduction  in  cost  of  production  would  prob- 
ably amount  to  $2  or  $3  a  cord. 

As  to  future  flotation-oil  values  it  is  difficult  to  conjecture.  The 
Bureau  of  Mines,  which  experimented  with  the  various  oils  obtained 
in  the  course  of  this  work,  commenting  on  the  conditions  that  will 
probably  have  to  be  met  in  the  flotation-oils  market  during  the 
coming  years,  points  out  that : 

Pine  oil  at  50  to  60  cents  per  gallon  has  cost  too  much.  Crude  petroleum 
and  coal  tar  containing  small  additions  of  pine  oil  can  be  made  to  do  almost 
the  same  grade  of  work  and  are  hence  cheapening  the  cost  of  flotation  oils. 
Pine  cresote,  pine  tar  oils,  and  various  hardwood  fractions,  together  with 
hardwood  tar,  are  finding  acceptance  in  place  of  the  more  expensive  products. 
There  will  always  be  a  market  for  pine  products,  however,  as  long  as  they 
do  not  cost  too  much;  30  to  40  cents  per  gallon,  f.  o.  b.  the  West,  will  probably 
be  the  price  paid  for  such  material  and  when  the  price  goes  much  above  that, 
the  material  will  merely  be  eliminated  from  consideration. 

Some  idea  of  the  quantities  of  these  pine  products  used  in  the  flota- 
tion of  ores  may  be  obtained  from  Table  20. 

TABLE  20. — Monthly  consumption  of  flotation  oils  in  the  United  States  (1916). 
[Compiled  from  a  report  of  the  Bureau  of  Mines.] 


Type  of  ore. 

Monthly  tonnage  of  ore. 

Wood  products. 

Beginning 
of  1916. 

End  of 
1916  (esti- 
mated). 

Pine 
oil.i 

Pine- 
tar  oil.2 

Oil  of 
eucalyp- 
tus. 

Wood 
creosote.3 

Crude 
turpen- 
tine. 

Copper  

Tons. 
1,248,000 
248,000 
115,000 
45,  700 

Tons. 
1,942,000 
350,000 
136,000 
123,000 

Galls. 
7,800 
8,000 
515 
1,300 

GaTls. 
95 

85 

Galls. 

Galls. 
47,600 
30,000 
13,800 
4  600 

Galls. 
205 
450 

Zinc  and  complex  . 

Lead 

28 

Gold  and  silver... 

95 

Total 

1,656,700 

2,551,000 

17,615 

275 

28 

96,000 

655 

1  Probably  includes  a  considerable  amount  of  the  lighter  fractions  of  pine-tar  oil. 

2  The  crude  light  oil  would  probably  come  in  this  class. 

3  The  crude  heavy  oil  would  probably  come  in  this  class. 

It  has  been  pointed  out  that  combinations  of  different  oils  are 
used  by  mixing  the  more  expensive  pine- wood  distillates  with  crude 
petroleum,  coal  tar,  etc.,  in  suitable  proportions  to  obtain  the  de- 
sired foaming  and  collecting  effect  for  the  kind  of  ore  to  be  treated. 
While  this  is  to  a  large  extent  done  at  concentration  plants,  some  pro- 
ducers in  the  East  market  blended  oils  on  this  same  principle.  This 
should,  of  course,  be  given  careful  consideration  by  those-who  may 


56  BULLETIN  1003    U.   S.   DEPARTMENT  OF  AGRICULTURE. 

engage  in  the  production  of  flotation  oils  from  resinous  wood  wastes 
in  the  Northwest.  A  list  of  uncompounded  pine  oils  and  other  dis- 
tilled wood  products  used,  either  alone  or  for  producing  blended  oils 
for  flotation,  is  given  herewith.  Some  idea  of  the  required  proper- 
ties may  be  derived  from  the  specific  gravities : 

Crude  pine  oil.  Pine-tar  oil,   double  refined    (sp.   gr., 

Crude  wood  turpentine.  0.965  to  0.990). 

Pine  oil,  steam  distilled  (sp.  gr.,  0.925  Pine  tar,  thin  (sp.  gr.,  0.980  to  1,0<M». 

to  0.940).  Wood  (pine)  creosote,  refined. 

Pine  oil,  destructively  distilled.  Hardwood    oil    (Michigan)     (sp.    gr., 

Pine-wood  oil  (light)    (sp.  gr.,  0.950).  0.960  to  0.990). 

Pine-wood  oil  (heavy)  ( sp.  gr.,  1.025 ).  Hardwood    oil    (Michigan)     (sp.    gr., 

Pine-taroil  (sp.gr.,  1.025 to  1.035).  1.06  to  1.08). 

REFINING  CRUDE  WOOD  TURPENTINE. 

The  crude  wood  turpentine  is  a  complex  mixture  of  oils,  both 
lighter  and  heavier  than  pinene,  certain  of  which  impart  to  the  tur- 
pentine an  objectionable,  penetrating  odor  and  dark  color,  from 
which  wood  turpentine  having  the  accepted  commercial  require- 
ments, and  of  uniform  quality,  is  to  be  obtained.  To  compare  favor- 
ably with  gum  spirits  the  refined  product  should,  in  addition  to  its 
odor  and  color,  have  a  correspondingly  narrow  boiling-point  range 
or  distillation-temperature  limits. 

In  refining  crude  wood  turpentine  it  is  customary  to  subject  it  to 
steam  distillation,  after  thorough  mixing  with  caustic  alkali  to  re- 
move or  hold  back  certain  constituents,  whereby  it  is  separated  into 
a  fraction  lighter  than  turpentine,  having  a  yellow  color  and  pene- 
trating odor,  a  turpentine  fraction,  and  a  pine-oil  fraction.  The  de- 
tails of  operation  and  the  proportion  and  quality  of  the  products 
thus  obtained  vary  greatly  with  the  quality  of  the  crude  oil,  as  well 
as  with  the  care  observed  in  dividing  or  cutting  the  fractions.  In 
doing  this  the  still  operator  is  commonly  guided  by  the  density,  odor, 
color,  etc.,  of  the  oil  in  changing  over  from  one  fraction  to  another, 
which  is  not  conducive  to  uniformity  of  results.  This  insufficient 
standardization  of  the  product  has  contributed  materially  to  the  un- 
favorable attitude  of  consumers  toward  wood  turpentine,  as  well 
as  to  the  lower  price  commanded  by  and  greater  difficulty  in  market- 
ing this  product  as  compared  with  gum  spirits. 

The  necessity  of  separating  a  light  fraction  that  must  be  marketed 
as  an  inferior  turpentine  or  special  product  because  of  its  objection- 
able odor  and  color,  moreover,  is  a  wasteful  practice,  in  that  this 
product  is  made  up  largely  of  pinene  which  properly  belongs  in  the 
turpentine  fraction.  Owing  further  to  imperfect  fractionation,  or 
the  tendency  of  the  heavier  oils  to  pass  over  with  the  turpentine, 
only  in  part  overcome  by  the  use  of  column  stills,  a  considerable 


DISTILLATION   OF  STUMPWOOD.  57 

proportion  of  the  turpentine  fraction  is  retained  in  the  residual 
pine  oil. 

Because  of  these  defects  in  refining  processes,  efforts  were  di- 
rected in  the  beginning  of  this  work  to  devise  a  laboratory  method 
for  recovering  a  maximum  of  high-grade  spirits  from  the  crude  oil 
that  would  be  applicable  to  the  operation  of  a  commercial  plant,  on 
the  basis  of  which  yields  of  commercial  turpentine  from  different 
woods  could  be  compared.  It  soon  became  apparent  that  sufficient 
importance  is  not  attached  to  the  amount  of  alkali  required  and  to 
the  manner  of  its  application.  Instructions  merely  to  distil  with 
alkali  or  to  treat  with  alkali  until  action  ceases  are  entirely  inade- 
quate, because  the  amount  of  alkali  used  materially  affects  the  pro- 
portion of  the  light  fraction,  the  sharpness  of  the  fractionation,  and 
the  quality  of  the  turpentine  as  indicated  by  its  odor,  color,  and  boil- 
ing point  limits.  The  intimacy  and  period  of  contact  of  the  alkali 
has  equal  or  greater  influence. 

The  alkali  appears  to  serve  a  double  purpose,  aside  from  that  of 
neutralizing  the  free  acid  present  in  the  crude  oil.  First,  it  brings 
an  apparent  polymerization  of  the  aldehydes  whereby  these  are  con- 
verted into  resinous,  nonvolatile  compounds,  in  which  form  their 
elimination  from  the  turpentine  is  effected  on  distillation.  Second, 
the  action  of  the  alkali,  if  used  in  sufficient  quantity,  results  in  the 
formation  of  a  soap  with  the  tar  and  resin  acids.  This,  in  a  man- 
ner not  understood,  although  it  may  be  through  formation  there- 
with of  a  so-called  water-soluble  oil,  restrains  the  escape  of  the 
pine-oil  constituents,  while  the  turpentine  distils  over,  thus  effect- 
ing a  materially  sharper  separation  of  the,  two.  The  alkali  solution 
being  immiscible  with  the  turpentine  and  the  polymerization  process 
partaking  in  its  nature  of  a  catalytic  or  surface  reaction,  the  effec- 
tiveness of  the  alkali  depends  on  extremely  intimate  contact  with 
the  turpentine  for  a  sufficient  length  of  time  to  permit  the  carrying 
of  the  reaction  to  completion  before  beginning  the  distillation.  It 
is  in  this  respect  that  refining  methods  as  ordinarily  carried  out  are 
wrong  in  principle,  for  the  reason  that,  with  the  alkali  added  in  the 
still,  distillation  begins  before  completion  of  the  reactions  that  "fix" 
the  aldehyde  bodies.  These  in  part  pass  over  with  the  turpentine 
and  are  removed  from  the  sphere  of  action  of  the  caustic  solution 
before  the  reactions  that  render  them  nonvolatile  have  been  com- 
pleted. Agitation  of  the  turpentine  in  a  separate  vessel  and  remov- 
ing and  distilling  the  oil  thus  separated  from  the  alkali  are  also 
wrong  in  principle,  because  advantage  is  not  taken  of  the  deterring 
action  of  the  soap  solution  on  the  distillation  of  pine  oils. 

To  combine  the  action  of  the  two  principles  here  set  forth  the 
crude  oil  is  agitated  with  caustic  soda  solution  at  boiling  tempera- 
ture in  a  return-flow  condensing  apparatus  before  distilling.  Me- 


58  BULLETIN  1003,   U.   S.   DEPARTMENT  OF  AGRICULTURE. 

chanical  agitation  with  a  paddle-wheel  stirring  device  was  the  first 
resort.  It  was  subsequently  found,  however,  that  heating  over  a 
flame  in  a  distilling  flask  fitted  with  return-flow  condenser  is  equally 
effective  and  much  simpler  in  execution.  This  method  of  treatment 
thoroughly  emulsifies  the  oil  and  caustic  solution,  giving  the  intimacy 
of  contact  desired,  while  the  inverted  condenser  continually  returns 
the  aldehyde  bodies  to  the  action  of  the  alkali  until  they  have  been 
changed  to  the  nonvolatile  products  previously  discussed.  The  in- 
verted condenser  is  then  replaced  by  a  Hempel  column  and  the  con- 
tents of  the  flask  distilled  with  steam,  yielding  from  the  start  a  tur- 
pentine of  standard  requirements. 

Steam  distillation  is  admirably  adapted  to  the  production  of  tur- 
pentine of  uniform  quality,  because  it  affords  a  simple  means  of  con- 
trol, in  that  the  ratio  of  oil  to  water  in  the  distillate  is  an  index  of 
the  composition  of  the  turpentine  (12).  This  is  a  gradually  dimin- 
ishing ratio  in  proportion  as  the  oil  contains  less  pinene  and  corre- 
spondingly more  of  the  higher-boiling  pine  oils.  For  any  observed 
oil-to-water  ratio,  however,  the  turpentine  has  a  definite  composition, 
as  indicated  by  its  density,  refractive  index,  distillation-temperature 
limit,  etc.  This,  of  course,  follows  from  the  law  of  relative  vapor 
pressure  of  immiscible  liquids.  Its  application  as  a  simple  and  re- 
markably accurate  means  by  which  to  judge  the  composition  of  the 
turpentine  at  any  time  during  the  distillation,  however,  has  not 
been  given  the  consideration  it  merits  (12)  as  a  means  of  standardiz- 
ing the  output  of  commercial  plants.  Properly  used,  the  oil-to-water 
ratio  makes  possible  the  production  of  turpentine  having  a  constant, 
predetermined  composition,  any  consignment  of  which  will  be  prac- 
tically the  same  as  a  preceding  or  subsequent  shipment. 

Following  up  preliminary  observations,  based  on  the  considera- 
tions set  forth,  a  series  of  experiments  was  conducted  to  determine : 
(a)  The  relative  efficiency  of  caustic  soda,  carbonate  of  soda,  and 
milk  of  lime  as  refining  agents;  (b)  the  proportion  of  alkali  to  crude 
oil  and  concentration  of  the  alkali  solution  giving  the  best  results; 
(c)  the  time  necessary  for  the  reactions  set  up  by  the  alkali  treat- 
ment to  produce  its  full  effect ;  (d)  the  effect  of  drawing  off  the  alkali 
after  treatment  and  washing  the  oil  with  water  before  distilling; 
(e)  the  effect  of  passing  a  current  of  air  through  the  oil  during  treat- 
ment with  alkali. 

In  carrying  out  these  experiments  500  cc.,  taken  from  a  large  com- 
posite sample  of  crude  western  yellow-pine  turpentine,  were  used  in 
each  test.  The  turpentine  fraction  proper  was  continued  to  where 
the  ratio  of  oil  to  water  was  4  to  6,  beyond  which  the  proportion 
changes  rapidly,  and  a  second  turpentine  fraction  collected  hot  \\  ecu 
the  4  to  6  and  3  to  7  ratios.  The  distillation  was  continued  for  the 


DISTILLATION   OF   STUMPWOOD.  59 

recovery  of  pine  oil  to  the  point  where  the  oil  constitutes  but  5 
per  cent  of  the  distillate  coming  over.  The  odor,  color,  refractive 
index,  density,  where  possible,  and  volume  of  each  fraction  thus  ob- 
tained by  the  different  methods  of  treatment  were  noted  in  order  to 
determine  by  the  comparison  of  these  constants  which  process  gives 
the  closest  separation  and  best  yield  of  high-grade  product. 

As  was  to  be  expected  the  best  results  were  obtained  by  the  use  of 
caustic  soda.  With  carbonate  of  soda,  used  in  such  proportion  that 
its  hydroxyl  strength  was  equivalent  to  that  of  the  hydrate,  the  quan- 
tity of  the  turpentine  recovered  from  the  crude  oil  was  the  same  as 
that  obtained  with  caustic  soda,  but  of  inferior  quality  with  respect 
to  odor.  For  commercial  use,  moreover,  the  fact  of  its  being  cheaper 
than  the  hydrate  is  offset  by  its  greater  equivalent  weight  and  the 
correspondingly  larger  quantity  required  to  produce  the  effect  of  an 
equivalent  amount  of  sodium  hydrate.  Milk  of  lime  has  only  low 
cost  to  recommend  it.  The  calcium  resinate  or  lime  soap  formed, 
being  insoluble,  does  not  form  the  pine-oil  emulsion  that  helps  ma- 
terially to  effect  a  sharp  separation  of  the  turpentine.  The  yield  of 
the  turpentine  is  lower  by  10  per  cent  than  when  sodium  hydrate  is 
used,  and  the  product  is  inferior  in  odor.  Moreover,  the  lime  soap 
seriously  fouls  the  apparatus  with  an  incrustation  difficult  to  remove. 

It  was  found  that  the  quality  improved  and  the  percentage  of  tur- 
pentine recovered  increased  with  increasing  amounts  of  alkali  up  to 
75  cc.  of  20  per  cent  caustic-soda  solution  per  500  cc.  of  crude  oil,  or, 
in  industrial  terms,  75  gallons  of  20  per  cent  caustic-soda  solution 
(containing  20  parts  per  hundred  of  actual  sodium  hydroxid)  to  500 
gallons  of  crude  turpentine.  This  proportion  was  found  to  be  satis- 
factory for  refining'  the  crude  second  turpentine.  For  the  crude  first 
turpentine  the  amount  of  alkali  probably  could  be  diminished.  The 
concentration  of  the  alkali  solution  is  not  so  important,  since  the  use 
of  half  this  quantity  of  40  per  cent  alkali  solution  does  not  materially 
affect  the  results.  The  duration  of  the  chemical  treatment  before  be- 
ginning the  distillation  is  of  great  importance,  and  at  least  30  min- 
utes after  the  mixture  reaches  the  boiling  point  should  be  allowed  for 
the  completion  of  the  reactions  involved.  Separation  of  the  alkali 
solution  from  the  turpentine  before  distilling  has  a  profound  effect. 
Not  only  is  the  quality  of  the  turpentine  much  inferior  to  that  of  the 
turpentine  obtained  when  the  distillation  is  made  in  the  presence  of 
the  alkali  solution,  but  the  yield  is  lower  by  20  per  cent,  with  a  corre- 
sponding increase  in  the  second  turpentine  and  pine-oil  fractions, 
showing  that,  however  brought  about,  the  soap  solution  exerts  a  re- 
straining influence  over  the  pine  oil,  the  complete  separation  of  which 
from  the  turpentine  is  most  essential  to  the  production  of  an  article 
possessing  the  properties  demanded  by  the  trade.  Passing  air  through 


60  BULLETIN  1003,   U.   S.   DEPARTMENT  OF  AGRICULTURE. 

the  oil  during  the  alkali  treatment  yields  a  turpentine  having  a 
sweeter  odor  than  that  obtained  without  aeration.  The  other  prop- 
erties and  the  yield  of  turpentine  recovered,  however,  are  not  mate- 
rially influenced  thereby.  In  refining  a  crude  oil  which  is  heavily 
charged  with  the  decomposition  products  of  destructive  distillation, 
aeration  to  improve  the  odor  may  be  found  advantageous. 

This  procedure  was  followed  in  refining  the  various  crude  turpen- 
tine samples  obtained: 

Transfer  a  500  cc.  portion  to  a  round-bottomed  liter  flask,  add  75  oc.  of  20 
per  cent  NaOH  solution,  and  some  finely  broken  pumice.  Attach  a  I  a  1-1:0  n-tlux 
condenser  and  heat  the  contents  to  and  maintain  at  the  boiling  temperature, 
over  a  gas  flame,  for  one-half  hour.  When  sufficiently  cooled,  to  avoid  loss, 
remove  the  reflux  condenser,  attach  a  Hempel  column  of  fairly  good  size 
filled  three-fourths  full  with  short  pieces  of  glass  tubing,  and  a  condenser  in 
the  ordinary  position,  and  distil  the  contents  of  the  flask  with  steam  in  the 
usual  manner.  The  oil  coming  over  to  where  the  ratio  of  oil  to  water  is 
4  to  6  is  first-quality  commercial  turpentine,  ready  to  enter  the  trade  as  such. 
That  coming  over  between  the  4  to  6  and  3  to  7  ratio  contains  a  small  pro- 
portion of  lighter  pine-oil  constituents,  and  needs  to  be  distilled  a  second  time 
for  their  complete  removal.  The  distillation  is  continued  for  the  recovery  of 
pine  oil  to  the  point  where  the  pine  oil  forms  5  per  cent  of  the  distillate 
coming  over  at  the  time,  below  which  ratio  it  was  not  deemed  economical  to  go. 

To  determine  quickly  the  proportion  of  oil  to  water  in  the  dis- 
tillate it  was  found  convenient  to  use  a  coordinate  paper  diagram 
(fig.  5),  in  which  abscissae  are  the  water  readings  and  ordinates  the 
total  distillate  readings  collected  during  a  short  interval.  Right 
lines  are  drawn  from  the  origin  of  coordinates  to  intersect,  at  100 
on  the  ordinate  axis,  the  points  60,  TO,  and  95  on  the  axis  of  abscissae, 
respectively,  these  corresponding  to  the  percentage  of  water  in  the 
distillate  at  the  transition  points.  To  use  the  diagram  for  deter- 
mining the  end  of,  say,  the  turpentine  fraction,  the  volumes  of  water 
and  total  distillate  are  read.  The  volumes  of  water  are  transferred  to 
the  horizontal  and  those  of  the  distillate  to  the  vertical  axis.  If 
the  intersection  falls  above  the  60  per  cent  water  line,  the  propor- 
tion of  oil  exceeds  40  per  cent,  and  similar  readings  are  taken  at 
suitable  intervals  until  it  falls  on  the  line.  Similarly,  the  TO  and 
95  per  cent  lines  determine  the  end  of  the  other  fractions. 

The  odor  and  color  of  the  refined  turpentine  samples  thus  obtained 
were  noted,  the  specific  gravity  and  refractive  index  determined,  and 
a  distillation  made  from  which  to  judge  their  quality  (Table  18). 

The  distillation  temperature  limits  of  turpentine  are  so  suscep- 
tible to  pressure  variation  that  it  is  essential,  in  making  such  com- 
parisons, to  conduct  the  distillation  under  normal  pressure.  The 
laboratory  at  Moscow,  Idaho,  being  at  an  elevation  of  about  2,800 
feet  above  sea  level,  it  was  necessary  to  increase  the  pressure  in  the 
distilling  apparatus  accordingly.  This  is  accomplished  by  means 


DISTILLATION   OF   STUMP  WOOD. 


61 


of  the  apparatus  devised  in  the  Bureau  of  Chemistry  and  described 
in  detail  in  Bureau  of  Chemistry  Bulletin  135,  "  Commercial  Tur- 
pentines." 

The  distillation  data,  along  with  the  other  data  thus  obtained, 
bring  out  a  striking  uniformity  in  the  physical  properties  of  cor- 
responding samples  from  various  sources,  differing,  however,  from 
the  better  quality  of  wood  turpentine  from  the  South  Atlantic  and 
Gulf  States  in  their  higher,  though  equally  narrow,  boiling  points. 


* 


* 


FIG.  5. — Proportion  of  oil  to  water  in  distillate. 

The  major  portion  of  turpentine  from  western  yellow  pine  dis- 
tilling between  iTO^and  175°  C.  instead  of  160°  and  165°  C.,  as  is  the 
case  with  gum  turpentine  obtained  from  southern  yellow  pine,  in- 
dicates that  in  place  of  alpha-pinene  this  turpentine  from  western 
yellow  pine  is  largely  made  up  of  beta-pinene  (7). 

To  obtain  a  closer  separation  of  its  constituents,  and  thereby  gain 
a  better  insight  into  the  proportion  and  nature  of  the  bodies  prob- 
ably entering  into  its  composition,  a  composite  sample  of  refined  first- 
grade  turpentine,  from  first  and  second  crude  turpentine  combined  in 


62 


BULLETIN    1003,   U.   S.   DEPARTMENT  OF   AGRICULTURE. 


proportions  as  recovered  from  the  crude  turpentine,  was  carefully 
distilled  from  a  Hempel  fractionating  apparatus,  and  the  boiling 
point,  specific  gravity,  and  refractive  index  curves  plotted  from  these 
data. 

The  boiling  point,  refractive  index,  and  specific  gravity  curves 
(figs.  6,  7,  8)  point  to  the  presence,  to  the  extent  of  about  2  per  cent, 


FIG.  6. — Boiling  point  of  distillate. 

of  a  body  distilling  at  a  relatively  low  temperature,  having  also  a 
much  lower  refractive  index  than  the  major  portion  of  the  distillate. 
This  is  probably  alpha-pinene,  which  in  a  pure  state  has  a  boiling 
point  of  155°  C.,  a  specific  gravity  of  0.858,  and  refractive  index  of 
1.4660  at  20°  C.,  whereas  the  corresponding  values  of  beta-pinene 
are  162°  C.,  0.868,  and  1.4784.  Polarimetrir  readings  on  the  first  two 
fractions,  up  to  6  per  cent  total  distillate,  showed  laevo-rotations,  in- 


DISTILLATION   OF   STUMPWOOD. 


63 


dicating  that  the  pinene  present  is  laevo-alpha-pinene.  Subsequent 
fractions  showed  dextro-rotations,  in  a  continually  advancing  degree. 
The  extra  high  density  of  the  first  distillate  to  come  over  is  to  be 
attributed  to  the  presence  of  traces  of  water,  held  in  solution  by 
small  quantities  of  methyl  alcohol,  known  to  occur  in  this  portion  of 
refined  turpentine  recovered  from  crude  second  turpentine,  and  also 
partly  to  the  presence  of  the  alpha-pinene.  As  the  distillation  pro- 


/O 


J?0 


n 


Tiff 


00 


cs/vr 

FIG.  7. — Refractive  index  of  distillate. 


gresses  the  specific  gravity  of  the  distillate  slowly  rises  with  the  boil- 
ing point  to  where,  at  about  20  per  cent  of  total  distillate,  the  presence 
of  a  body  having  a  specific  gravity  lower  than  that  of  the  distillate 
immediately  preceding  it  again  asserts  itself  by  a  bending  back- 
ward of  the  specific-gravity  curve  at  this  point.  This  may  be  due  to 
the  presence  of  one  or  more  of  several  bodies,  the  most  probable 
of  which  is  limonene  or  dipentene  (specific  gravity  0.845,  refractive 


64 


BULLETIN   1003,   U.   S.   DEPARTMENT  OK    AGRICULTURE. 


index  1.4730,  each  at  20°  C.,  boiling  point  178°  C.),  dipentene  being 
known  to  be  a  constitutent  of  wood  turpentine.  A  materially  higher 
temperature  than  the  boiling  point  of  betapinene  at  which,  even  from 
the  beginning,  the  turpentine  distils,  points  further  to  the  presence 
of  appreciable  amounts  of  dipentene,  the  greater  portion  of  the 
turpentine  distilling  at  a  temperature  intermediate  between  that  of 
beta-pinene  and  dipentene.  Above  80  per  cent  of  total  distillate  the 


60        TO       #0        00      /Off 


FIG.  8. — Specific  gravity  of  distillate. 

boiling  point,  specific  gravity,  and  refractive  index  rise  rapidly, 
showing  that  the. composition  of  the  distillate  is  undergoing  a  further 
marked  change. 

The  principal  constituents  of  turpentine,  collectively  spoken  of 
as  terpenes,  are  a  closely-related  series  of  organic  compounds  pos- 
sessing such  a  close  similarity  in  chemical  and  physical  properties 
that  precise  knowledge  concerning  their  quantitative  estimation  has 


DISTILLATION   OF  STUMPWOOD.  65 

not  as  yet  been  placed  on  a  satisfactory  basis.  The  problem  is  ren- 
dered more  difficult  because  of  the  tendency  exhibited  by  the  ter- 
penes  as  a  class  to  pass  readily  from  one  form  to  another,  and,  in 
addition,  to  combine  with  oxygen  and  the  elements  of  water,  under 
conditions  not  well  understood,  to  form  a  series  of  altogether  more 
complex,  oxygenated  bodies  possessing  properties  entirely  different 
from  those  of  the  parent  substance. 

Hesitation  is  felt,  therefore,  in  assigning  numerical  relations  to 
or  making  an  apportionment  of  the  constituents  that  appear  to  enter 
into  the  composition  of  this  turpentine  further  than  to  say  that  it 
seems  to  be  largely  made  up  of  beta-pinene  and  dipentene,  or  its 
optically  active  modification,  d-limonene,  a  small  proportion,  5  per 
cent  or  less,  of  alpha-pinene  containing  perhaps  some  camphene, 
and  about  15  or  20  per  cent  of  relatively  high-boiling  terpene  de- 
rivatives of  unknown  composition.  The  boiling-point  and  specific- 
gravity  curves  indicate  that  the  proportion  of  dipentene,  or  limonene, 
probably  exceeds  that  of  beta-pinene. 

To  what  extent  ordinary  turpentine  possesses  "drying"  power,  in 
the  sense  of  being  an  oxygen  carrier,  is  an  open  question  in  the 
chemistry  of  paints  and  varnishes,  and  the  relative  oxygen-trans- 
ferring power  of  beta-pinene  compared  to  that  of  alpha-pinene  has 
not  been  determined.  Kremers  (5)  found  that  limonene  absorbs 
oxygen  quite  as  rapidly  as  does  pinene,  from  which  it  may  be  in- 
ferred that  dipentene  possesses  this  property  to  a  like  degree. 

To  what  extent  the  relatively  high  distilling  temperature  of  tur- 
pentine from  western  yellow  pine  will  influence  its  value  for  use 
in  paints,  varnishes,  etc.,  can  be  definitely  determined  only  from 
actual  use.  The  results  obtained  in  comparative  evaporation  tests, 
at  room  temperature,  of  gum  spirits  and  wood  turpentine  from  the 
South,  and  wood  turpentine  from  western  yellow  pine,  secured  in 
the  course  of  this  work,  however,  show  that  the  product  from  the 
western  yellow  pine  is  materially  slower  in  evaporating  than  either 
the  gum  or  wood  spirits  from  the  South.  Moreover,  the  film  re- 
maining from  the  evaporation  of  the  western  yellow-pine  wood 
turpentine  after  drying  twice  as  long  as  that  from  either  of  the 
others  could  not,  properly  speaking,  be  said  to  have  become  dry  or 
resinified,  compared  with  the  films  from  the  other  samples.  This 
fact  is  undoubtedly  due  to  the  high-boiling  constituents,  the  approxi- 
mately 20  per  cent  which  distils  above  175°  C.  If  this  material 
were  not  mixed  with  the  turpentine  where  it  does  not  belong,  but 
were  added  to  the  pine  oil  which  it  actually  is,  the  turpentine  would 
dry  much  more  rapidly  and  be  more  acceptable  as  a  paint  and  var- 
nish thinner.  For  some  purposes,  however,  a  slow-drying  solvent  is 
desired,  in  which  case  the  presence  of  the  high-boiling  constituent  is 
00953°— 21 5 


66  BULLETIN  ,1003,   U.    S.   DEPARTMENT  OF   AGRICULTURE. 

beneficial.  The  solvent  power  of  this  turpentine  appears  to  be 
equal  to  that  of  turpentine  from  ordinary  sources,  and  it  is  quite 
as  light  in  color.  Its  odor,  while  different  from  that  of  gum 
spirits,  is  in  no  way  objectionable,  the  main  point  of  distinction  in 
this  respect  being  the  pine  wood  odor  so  characteristic  of  the  better 
quality  of  wood  turpentine  generally. 

While  not  suitable  perhaps  for  all  the  technical  uses  to  which 
ordinary  turpentine  is  adapted,  this  turpentine  will  answer  for  most 
such  purposes  and  it  should  find  a  ready  market  if  properly  intro- 
duced to  the  trade. 

APPLICATION  OF  METHOD  TO  THE  COMMERCIAL  PLANT. 

The  method  of  refining  crude  turpentine  just  described  is  readily 
adaptable  to  the  commercial  plant.  Two  procedures  may  be  fol- 
lowed, according  to  the  size  of  the  plant  and  the  available  capital 
for  investment.  The  simplest  and  cheapest  equipment  for  refining 
the  crude  wood  turpentine  is  a  single  copper  refining  still,  so  fitted 
with  a  water-cooled  return-flow  condenser  and  a  short  fractionating 
column  and  condenser,  of  any  efficient  type,  that  either  one  may 
be  used  singly.  After  suspended  and  undissolved  tarry  matter  has 
had  an  opportunity  to  settle  out,  the  crude  turpentine  is  drawn  into 
the  still,  where  it  is  mixed  with  the  proper  quantity  of  caustic  soda 
solution  and  boiled  for  the  prescribed  length  of  time,  with  the 
return-flow  condenser  open  and  the  fractionating  column  shut  off 
from  the  system.  The  heat  for  bringing  the  contents  of  the  still  to 
a  boil  can  be  obtained  either  directly  from  a  furnace  under  the  still 
or  from  closed  steam  coils  inside  the  still  at  the  bottom.  The  steam 
coils  are  the  safer  arrangement.  An  open  steam  coil,  with  a  number 
of  small  openings  along  the  length  of  the  coil,  is  also  placed  inside 
the  still  with  the  closed  coil.  This  open  coil  may  be  connected  by  a 
proper  arrangement  of  piping  and  valves  to  both  the  boiler  and  a 
small  air  compressor,  and  used  during  the  preliminary  boiling  to 
aerate  the  turpentine  and  alkali  mixture. 

At  the  end  of  the  preliminary  boiling  period  the  fractionating 
column  is  opened,  the  return-flow  condenser  closed,  and  steam  turned 
on  in  the  open-coil  system.  The  turpentine  and  pine  oil  are  distilled 
off  with  the  steam  and  collected  in  three  fractions,  as  already  out- 
lined (p.  58).  Toward  the  end  of  the  distillation  additional  heat 
may  be  supplied  by  again  turning  high-pressure  steam  into  the 
closed  coil,  to  help  drive  over  the  last  portions  of  pine  oil.  At  the 
end  of  the  distillation  the  alkali  residuum  is  drawn  off  from  the 
still.  The  same  still  may  be  used  for  the  subsequent  refrartionation 
of  the  various  fractions  from  the  first  distillation. 

A  more  expensive  arrangement,  that  probably  is  better  adapted 
to  a  larger  plant,  consists  of  two  separate  stills,  the  first  of  which, 


DISTILLATION   OF   STUMPWOOD.  67 

for  the  preliminary  boiling  with  alkali,  is  fitted  with  the  return- 
flow  condenser.  At  the  end  of  the  period  of  boiling  the  contents  are 
drawn  off  into  a  second  steam  still  with  a  short  fractionating  column. 
With  this  arrangement  the  operation  can  be  conducted  almost  con- 
tinuously. As  soon  as  the  charge,  after  preliminary  boiling,  is 
drawn  into  the  steam-refining  still,  a  new  charge  of  crude  turpen- 
tine can  be  drawn  from  the  settling  tanks  into  the  first  still. 

In  a  large  plant  the  final  refractionation  of  the  first  steam-dis- 
tilled fractions  can  very  well  be  carried  out  in  a  small  continuous 
fractionating  still  fitted  with  a  short  column. 

The  alkali  residuum,  which  consists  partly  of  pine  and  tar  oil, 
with  the  sodium  soaps  of  tar  and  resin  acids,  and  an  excess  of  alkali, 
has  been  shown  by  test  to  have  germicidal  properties  approximately 
half  as  great  as  those  of  phenol.  Its  probable  use  as  a  local  disin- 
fectant, after  partial  neutralization  of  the  free  alkali  with  the 
waste  acid  liquor,  is  thereby  suggested.  Probably  it  can  be  used, 
after  the  addition  of  a  small  amount  of  coal-tar  creosote,  as  the 
basis  of  a  dip  for  hogs  to  rid  them  of  lice.  No  actual  experiments 
to  determine  the  real  value  of  this  material  have  been  made.  It  is 
impossible,  therefore,  to  give  concise  directions  for  its  use. 

SUMMARY. 

(1)  In  general,  the  stumps  of  western  yellow  pine  are  not  as 
uniformly  rich  in  resin  as  those  of  the  longleaf  yellow  pine  in  the 
South  Atlantic  and  Gulf  States. 

(2)  The  only  wastes  from  western  yellow-pine  logging  suitable 
for  profitable  distillation  on  a  commercial  scale  are  those  resinous 
stumps  which  contain  at  least  50  per  cent  or  more  of  resinous  heart  - 
wood,  and  the  resinous  heartwood  of  stumps,  dead,  down  wood,  and 
limbs  from  which  the  sapwood  has  rotted  away. 

(3)  It  is  impossible  to  classify  western  stumps  into  such  grades 
as  "  rich  "  or  "  pitchy,"  "  medium,"  and  "  poor  "  merely  by  a  super- 
ficial examination  of  the  quantity  of  resinous  exudation  on  the  face 
of  the  stump. 

(4)  "  Rich  "  stumps,  containing  not  less  than  60  per  cent  of  very 
resinous  heartwood,  probably  can  be  profitably  distilled  in  a  com- 
mercial plant  where  the  stand  of  such  stumps  is  dense  enough  to 
keep  a  plant  supplied  for  a  number  of  years. 

(5)  Owing  to  the  fact  that  there  is  a  well-developed  market  in 
the  West  for  crude  pine-wood  oils  for  use  in  the  flotation  concentra- 
tion of  ores,  and  also  to  the  small  volume  of  "  rich  "  wood  obtain- 
able within  hauling  distance,  it  is  probable  that  single  retort  plants, 
which  can  be  dismantled  and  moved  when  necessary,  are  the  most 
suitable  for  wood  distillation  in  that  section  of  the  country,  espe- 


68  BULLETIN   1003,   U.   S.   DEPARTMENT  OF  AGRICULTURE. 

cially  in  regions  remote  from  the  railroad.     Such  plants  might  be 
owned  and  operated  jointly  by  a  number  of  settlers. 

(6)  "  Medium  "  grade  stumps,  though  much  more  plentiful  than 
"  rich  "  stumps,  could  be  used  in  a  commercial  plant  only  at  a  cost, 
delivered,  materially  less  than  the  calculated  cost  per  cord  of  such 
wood,  $8.37,  and  at  prices  for  products  not  materially  less  than 
those  given  in  this  bulletin. 

(7)  The  refined  turpentine  from  western  yellow-pine  stump  wood, 
consisting  mostly  of  beta-pinene  and  limonene,  has  higher  boiling- 
point  limits  than  similar  turpentine  from  southern  yellow  pine,  and 
dries   much   more  slowly.     For  this  reason   paints   and  varnishes 
thinned  with  the  turpentine  take  longer  to  dry  than  the  same  paints 
and  varnishes  thinned  with  turpentine  made  from  the  longleaf  yellow 
pine  of  the  South. 

(8)  The  solvent  power  of  this  turpentine  is  not  less  than  that  of 
wood  turpentine  from  longleaf  yellow  pine  made  and  refined  by  the 
same  process.    It  is  suitable  for  many  if  not  all  of  the  purposes  for 
which  wood  turpentine  can  be  employed. 

(9)  The  refined  pine  oil  and  the  crude  oils  obtained  by  distilling 
western  yellow  pine  are  valuable  for  ore  recovery  by  the  flotation 
process.     This  is  probably  the  most  profitable  use  to  which  these 
products  can  be  put. 

(10)  The  crude  light  and  heavy  oils  have  germicidal  properties 
approximately  half  as  great  as  those  of  phenol,  for  which  reason 
they  are  useful  for  shingle  stains,  wood  preservatives,  vermin  killers, 
and  disinfectants. 

(11)  The  pyroligneous  acid  or  "acid  liquor"  contains  approxi- 
mately one-fourth  the  amount  of  acetic  acid,  methyl  alcohol,  and 
acetone  ordinarily   recovered  from   hardwood   acid  liquor,   and  is 
heavily  charged  with  dissolved  tarry  matter,  resembling  in  all  re- 
spects the  pyroligneous  acid  obtained  in  distilling  southern  yellow- 
pine  wood.     At  the  usual  prices,  the  recovery  of  these  materials  at 
a  profit  is  hardly  possible  by  present  methods. 

(12)  A  simple  method  for  the  commercial  refining  of  crude  wood 
turpentine,  which  yields  a  superior  product,  has  been  devised. 

The  figures  given  in  this  bulletin  are  based  on  those  which  pre- 
vailed in  1914  and  1915.  Prices  have  increased  materially  since  that 
time  and  estimated  profits  may  be  more  or  less.  Material  changes  in 
the  ratio  of  total  cost  of  production  to  selling  value  of  products 
will  increase  the  calculated  profits  from  wood  distillation  if  the 
value  of  products  has  risen  faster  than  cost  of  materials  and  of  pro- 
duction. Calculated  profits  will  be  decreased  if  the  materials  and 
cost  of  production  have  increased  more  than  the  value  of  the  products 
of  distillation.  In  order  to  estimate  at  any  given  time  the  probable 


DISTILLATION   OF   STUMPWOOD.  69 

profits  from  distilling  western  yellow -pine  wood,  costs  and  values 
must  be  calculated  on  the  basis  of  the  cost  of  labor,  wood,  equip- 
ment, overhead,  etc.,  and  on  the  basis  of  the  value  of  the  products, 
at  the  time  the  estimate  is  made. 

LITERATURE  CITED. 

(1)  BERRY,  S.    Lumbering  in  the  sugar  and  yellow  pine  region  of  California. 

U.  S.  Dept.  Agr.  Bull.  440.  1917. 

(2)  BETTS,  H.  S.    Possibilities  of  Western  pines  as  a  source  of  naval  stores. 

U.  S.  Dept.  Agr.,  Forest  Service  Bull.  116.  1912. 

(3)  GRAVES,  H.  S.,  and  ZIEGLER,  E.  A.,    The  woodsman's  handbook.    U.  S. 

Dept.  Agr.,  Forest  Service  Bull.  36.  1910. 

(4)  HALL,  W.  L.,  and  MAXWELL,  H.     Uses  of  commercial  woods  of  the  United 

States :  II.  Pines.     U.  S.  Dept.  Agr.,  Forest  Service  Bull.  99.  1911. 

(5)  KREMERS,  E.    Notes  on  coniferous  oils:  II.  Oil  from  Pinus  sabwiana.    In 

Pharm.  Rev.,  18:  165-172.  1900. 

(6)  HUNGER,  T.  T.     Western  yellow  pine  in  Oregon.    U.  S.  Dept.  Agr.  BulL 

418.  1917. 

(7)  SCHORGER,  A.  W.    An  examination  of  the  oleoresins  of  some  Western 

pines.     U.  S.  Dept.  Agr.,  Forest  Service  Bull.  119.  1913. 

(8)  SHATTUCK,  C.  H.     Methods  of  clearing  logged-off  land.    Univ.  Idaho  Agr. 

Expt.  Sta.  Bull.  91.  1916. 

(9)  SMITH,  F.  H.,  and  PIERSON,  A.  H.     Production  of  lumber,  lath,  and  shingles 

in  1916.     U.   S.  Dept.  Agr.  Bull.  673.  1918. 

(10)  SUDWORTH,  G.  B.     The  pine  trees  of.  the  Rocky  Mountain  region^  U.  S. 

Dept.  Agr.  Bull.  460.  1917. 

(11)  THOMPSON,  H.     Cost  and  methods  of  clearing  land  in  western  Washington. 

U.  S.  Dept.  Agr.,  B.  P.  I.  Bull.  239.  1912. 

(12)  VEITCH,  F.  P.,  and  DONK,  M.  G.    Wood  turpentine:  Its  production,  refin- 

ing, properties,  and  uses.    U,  S.  Dept.  Agr.,  Bur.  Chem.  Bull.  144.  1911. 

(13)  WOOLSEY,  T.  S.,  JR.    Western  yellow  pine  in  Arizona  and  New  Mexico. 

U.  S.  Dept.  Agr.,  Forest  Service  Bull.  101.  1911. 


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